Surgical apparatus having a frame and moving support structure and method therefore

ABSTRACT

A surgical apparatus is configured to support at least one bone cut for installation of a prosthetic component. The installed prosthetic component will have reduced alignment error. The surgical apparatus is configured to distract a first compartment to a first predetermined load value while allowing a moving support structure to pivot freely. A distraction lock mechanism is then engaged to prevent movement of a distraction mechanism that raises or lowers the moving support structure relative to a fixed support structure. The moving support structure has M-L tilt angle that is measured. A M-L tilt mechanism is engaged to forcibly equalize the first and second compartments. Engaging the M-L tilt mechanism prevents the moving support structure from freely pivoting. The at least one bone cut relates to the first and second compartments equalized and the M-L tilt angle.

FIELD

The present disclosure relates generally to orthopedic medical devices,and more specifically to devices that generate quantitative measurementdata in real-time.

BACKGROUND

The skeletal system of a mammal is subject to variations among species.Further changes can occur due to environmental factors, degradationthrough use, and aging. An orthopedic joint of the skeletal systemtypically comprises two or more bones that move in relation to oneanother. Movement is enabled by muscle tissue and tendons attached tothe skeletal system of the joint. Ligaments hold and stabilize the oneor more joint bones positionally. Cartilage is a wear surface thatprevents bone-to-bone contact, distributes load, and lowers friction.

There has been substantial growth in the repair of the human skeletalsystem. In general, prosthetic orthopedic joints have evolved usinginformation from simulations, mechanical prototypes, and patient datathat is collected and used to initiate improved designs. Similarly, thetools being used for orthopedic surgery have been refined over the yearsbut have not changed substantially. Thus, the basic procedure forreplacement of an orthopedic joint has been standardized to meet thegeneral needs of a wide distribution of the population. Although thetools, procedure, and artificial joint meet a general need, eachreplacement procedure is subject to significant variation from patientto patient. The correction of these individual variations relies on theskill of the surgeon to adapt and fit the replacement joint using theavailable tools to the specific circumstance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an orthopedic measurement system generatingquantitative measurement data to support installation of a prostheticcomponent in accordance with an example embodiment;

FIG. 2 is an illustration of the orthopedic measurement systemdistracting a knee joint of a leg in accordance with an exampleembodiment;

FIG. 3 illustrates the cover, the module, and the distractor inaccordance with an example embodiment;

FIG. 4 illustrates a cover on the module configured having ananterior-posterior (A-P) slope of zero in accordance with an exampleembodiment;

FIG. 5 illustrates a cover on the module configured having ananterior-posterior (A-P) slope of 2 degrees in accordance with anexample embodiment;

FIG. 6 illustrates a cover on the module configured having ananterior-posterior (A-P) slope of 4 degrees in accordance with anexample embodiment;

FIG. 7 illustrates a cover on the module configured to interface withnatural condyles of the femur in accordance with an example embodiment;

FIG. 8 illustrates a cover having a support structure on the moduleconfigured to interface with a femoral prosthetic component inaccordance with an example embodiment;

FIG. 9 illustrates a cover on the module configured to interface with afemoral prosthetic component having a support structure coupled to afemur in accordance with an example embodiment;

FIG. 10A illustrates the frame and a frame retaining support structurein accordance with an example embodiment;

FIG. 10B illustrates the frame coupled to the frame retaining supportstructure in accordance with an example embodiment;

FIG. 11 illustrates different frame sizes in accordance with an exampleembodiment;

FIG. 12A illustrates the moving support structure disengaged from theM-L tilt mechanism in accordance with an example embodiment;

FIG. 12B illustrates the moving support structure coupled to M-L tiltmechanism in accordance with an example embodiment;

FIG. 13 is an illustration of the M-L tilt mechanism in accordance withan example embodiment;

FIG. 14 is an illustration of the distraction mechanism in accordancewith an example embodiment;

FIG. 15 is a block diagram of electronic circuitry in the distractor ofFIG. 1 or the module of FIG. 1 in accordance with an example embodiment;

FIG. 16 is an illustration of a magnetic angle sensor coupled to the M-Ltilt mechanism in accordance with an example embodiment;

FIG. 17 is an illustration of the magnetic angle sensor in thedistractor in accordance with an example embodiment;

FIG. 18 is an illustration of the moving support structure tiltinglaterally in accordance with an example embodiment;

FIG. 19 is an illustration of a magnetic distance sensor in thedistractor in accordance with an example embodiment;

FIG. 20 is an illustration of the display of the computer as shown inFIG. 1 in accordance with an example embodiment;

FIG. 21 is an illustration of a top view of the module in accordancewith an example embodiment;

FIG. 22 is an illustration of the module with a portion of an enclosureremoved in accordance with an example embodiment;

FIG. 23 is an exploded view of an insert prosthetic component inaccordance with an example embodiment;

FIG. 24 is an anterior view of the insert installed on a tibialprosthetic component in accordance with an example embodiment;

FIG. 25 is a side view of the insert installed on the tibial prostheticcomponent in accordance with an example embodiment;

FIG. 26 illustrates a step in a knee joint installation procedure inaccordance with an example embodiment;

FIG. 27 illustrates a step of placing the distractor in the knee jointof the leg in accordance with an example embodiment;

FIG. 28 illustrates a step of displaying the distraction distance dataand the M-L tilt angle on a display in real-time in accordance with anexample embodiment;

FIG. 29 illustrates a step of increasing the distraction distance untila predetermined loading is achieved in accordance with an exampleembodiment;

FIG. 30 illustrates a step of reviewing the position of load, the loadmagnitude, M-L tilt angle, and the distraction distance on the displayas the distraction distance of the distractor is increased in accordancewith an example embodiment;

FIG. 31 illustrates a step of reviewing an x-ray in accordance with anexample embodiment;

FIG. 32 illustrates an equalizing step where the M-L angle of the movingsupport structure is adjusted in accordance with an example embodiment;

FIG. 33 illustrates a step of monitoring equalization of the femur onthe display in accordance of an example embodiment;

FIG. 34 illustrates a step of drilling guide holes in the femur inaccordance with an example embodiment;

FIG. 35 illustrates a step of removing a drill guide and drill guideholder from the distractor in accordance with an example embodiment;

FIG. 36 illustrates a step of reducing the distraction distance of thedistractor and placing the leg in flexion in accordance with an exampleembodiment;

FIG. 37 illustrates a step of adjusting the distraction distance whilethe leg is in flexion in accordance with an example embodiment;

FIG. 38 illustrates a step of equalizing the medial gap and the lateralgap with the leg in flexion in accordance with an example embodiment;

FIG. 39 illustrates a step of placing a sizer on the distractor tosupport selection of a femoral prosthetic component in accordance withan example embodiment;

FIG. 40 illustrates a step of coupling a femur coupler to the femur withthe leg in flexion in accordance with an example embodiment;

FIG. 41 illustrates a step of providing a plurality of sizers to supportselection of the femoral prosthetic component;

FIG. 42 illustrates a step of drilling one or more holes in the distalend of the femur in flexion in accordance with an example embodiment;and

FIG. 43 illustrates one or more holes drilled in the distal end of thefemur in accordance with an example embodiment;

FIG. 44 is an illustration of an alternate embodiment of a distractor inaccordance with an example embodiment;

FIG. 45 is an illustration of the alternate embodiment of the distractorwith a transparent housing to illustrate components therein inaccordance with an example embodiment;

FIG. 46 illustrates a step in a knee joint installation procedurerelated to the alternate embodiment of the distractor shown in FIG. 44in accordance with an example embodiment;

FIG. 47 illustrates a step in the knee joint installation procedurerelated to the alternate embodiment of the distractor wherein the knobis rotated counter clockwise in accordance with an example embodiment;

FIG. 48 illustrates a step in the knee joint installation procedurerelated to the alternate embodiment of the distractor coupling to thefemur in accordance with an example embodiment;

FIG. 49 illustrates the step in a knee joint installation procedurerelated to the alternate embodiment of the distractor where the lateralplate and the medial plate contact the femur in accordance with anexample embodiment;

FIG. 50 illustrates a step in the knee joint installation procedurerelated to the alternate embodiment of the distractor where equalizationof the medial gap and the lateral gap occurs in accordance with anexample embodiment;

FIG. 51 depicts an exemplary diagrammatic representation of a machine inthe form of a system in accordance of an example embodiment; and

FIG. 52 is an illustration of a communication network for measurementand reporting in accordance with an exemplary embodiment.

DETAILED DESCRIPTION

The following description of exemplary embodiment(s) is merelyillustrative in nature and is in no way intended to limit the invention,its application, or uses.

Processes, techniques, apparatus, and materials as known by one ofordinary skill in the art may not be discussed in detail but areintended to be part of the enabling description where appropriate.

While the specification concludes with claims defining the features ofthe invention that are regarded as novel, it is believed that theinvention will be better understood from a consideration of thefollowing description in conjunction with the drawing figures, in whichlike reference numerals are carried forward.

The example embodiments shown herein below of the surgical apparatus areillustrative only and does not limit use for other parts of a body. Thesurgical apparatus can be used to measure, distract, align, cut, andsupport installation of prosthetic components to the musculoskeletalsystem. The surgical apparatus can be used on the knee, hip, ankle,spine, shoulder, hand, wrist, foot, fingers, toes, and other areas ofthe musculoskeletal system. In general, the principles disclosed hereinare meant to be adapted for use in other locations of themusculoskeletal system.

FIG. 1 is an illustration of an orthopedic measurement system 1generating quantitative measurement data to support installation of aprosthetic component in accordance with an example embodiment.Orthopedic measurement system 1 comprises a distractor 10, a module 32,and a computer 12. Distractor 10 can also be called a surgicalapparatus, device, or tool. Distractor 10 is not limited to distractionbut can perform other functions such as alignment, bone cuts, andparameter measurement to name but a few. Distractor 10 includes at leastone sensor configured to generate quantitative measurement data.Similarly, module 32 includes at least one sensor configured to generatequantitative measurement data. Distractor 10 and module 32 each includeselectronic circuitry configured to control a measurement process andtransmit measurement data to computer 12. Computer 12 includes a display14 configured to display the quantitative measurement data received fromdistractor 10 and module 32, analyze the measurement data, providevisual, haptic, or audible feedback related to the measurement data, andprovide a workflow in support of an optimal installation based on themeasurement data. In one embodiment, a distraction distance ofdistractor 10 and an M-L tilt angle of moving support structure 30 ismeasured and displayed on display 14 of computer 12.

Distractor 10 comprises a housing 20, distraction mechanism 24,medial-lateral (M-L) tilt mechanism 22, a fixed position supportstructure 28, and a moving support structure 30. In one embodiment, M-Ltilt mechanism 22 couples between distraction mechanism 24 and fixedposition support structure 28. Housing 20 partially houses distractionmechanism 24. A knob 26 or handle couples to distraction mechanism 24 toallow a user to increase or decrease a distraction distance ofdistractor 10. Housing 20 retains distraction mechanism 24 and supportsmovement of distraction mechanism 24 in a predetermined directionrelative to fixed position support structure 28. In the exampleembodiment, fixed position support structure 28 couples to housing 20and distraction mechanism 28 and moves perpendicular to a bottom surface34 of fixed support structure 28. Moving support structure 30 couples toM-L tilt mechanism 22. Distraction mechanism 24 couples to M-L tiltmechanism 22 and is configured to raise or lower M-L tilt mechanism 22and moving support structure 30 relative to fixed support structure 28.A distraction mechanism lock 38 is configured to lock distractionmechanism 24 from moving thereby holding a distance between movingsupport structure 30 and fixed support structure 28 constant.

M-L tilt mechanism 22 is configured to medially or laterally tilt movingsupport structure 30. A key or knob couples to M-L tilt mechanism 22 tochange the M-L tilt. M-L tilt mechanism 22 can be disengaged from movingsupport structure 30 such that moving support structure 30 can freelytilt medially or laterally depending on how moving support structure 30is loaded. Module 32 couples to and is supported by moving supportstructure 30. In one embodiment, module 32 couples to a major surface ofmoving support structure 30. A cover couples to module 32. The cover isremovable and is an interface to the distal end of femur 16.

As shown in FIG. 1 the distraction distance of distractor 10 is at aminimum height. In the example, the proximal end of tibia 18 has aprepared surface. The prepared surface can be a planar surface and canalso have a predetermined anterior-posterior (A-P) slope. In general,the word predetermined used herein above and below corresponds to a userselected value. The use of the word predetermined does not imply aspecific value or range. A minimum distraction distance of distractor 10occurs when surface 34 of fixed support structure 28 and a bottomsurface of moving support structure 30 couples to the prepared surfaceof the proximal end of tibia 18. The distraction distance is thedistance between the distal end of femur 16 and a proximal end of tibia18 under distraction. Note that the cover couples to the condyles offemur 16 and fixed support structure 28 couples to the prepared surfaceof the proximal end of tibia 18. The distance between the cover and thefixed support structure corresponds to the distraction distance. In oneembodiment, fixed support structure 28 comprises a frame 36. Frame 36has an opening for receiving moving support structure 30 therebyallowing the bottom surface of moving support structure 30 to couple tothe prepared bone surface of tibia 18.

FIG. 2 is an illustration of orthopedic measurement system 1 distractinga knee joint of a leg in accordance with an example embodiment. Asshown, the leg is in extension. Surface 34 of fixed support structure 28couples to prepared surface 40 of the proximal end of tibia 18. Knob 26couples to distraction mechanism 24. Rotating knob 26 increases ordecreases separation between moving support structure 30 and fixedsupport structure 28. In the example, knob 26 is rotated to increase thedistraction distance such that a bottom surface 42 of moving supportstructure 30 does not touch prepared bone surface 40. Module 32 andcover 38 are supported by moving support structure 30. Cover 38 couplesto the condyles of the distal end of femur 16. Thus, the distractiondistance includes the thickness of module 32 and cover 38 and ismeasured from the distal end of femur 16 to the prepared surface oftibia 18.

Distractor 10 includes a distance sensor on distractor 10 configured tomeasure the distraction distance. In one embodiment, the distance sensorcouples to distraction mechanism 24. Similarly, distractor 10 includesan angle sensor configured to measure the M-L tilt angle of movingsupport structure 30. In one embodiment, the angle sensor couples to theM-L tilt mechanism 22. Distractor 10 includes electronic circuitrycoupled to the distance sensor and the angle sensor. The electroniccircuitry of distractor 10 controls a measurement process and transmitsmeasurement data to computer 12. The measurement data can comprisedistraction distance data and M-L tilt data from the distance sensor andthe angle sensor. The distraction distance data and M-L tilt data can bedisplayed on display 14 in real-time. Alternatively, distractor 10 canhave a mechanical distance gauge and a M-L tilt gauge on distractor 10.

Module 32 also includes electronic circuitry and one or more sensors. Inone embodiment, module 32 includes a plurality of load sensorsconfigured to measure loading applied to the cover 38. The load sensorsare configured to measure load magnitudes at predetermined locations oncover 38. The electronic circuitry of module 32 is configured to controla load measurement process and transmit load data. Load data istransmitted from module 32 to computer 12. Computer 12 can process theload data from the plurality of load sensors (at predeterminedlocations) and calculate a load magnitude and a position of load where acondyle of femur 16 couples to cover 38. Computer 12 can providevisualization of the data to aid a surgeon in rapidly absorbing thequantitative measurement data. For example, a surface 48 of cover 38 orthe surface of module 32 can be shown on display 14 of computer 12.Contact points 44 and 46 can indicate where each condyle couples tocover 38. The contact points 44 and 46 can move in real-time if a changeoccurs that results in a parameter change that affects the contactpoints. For example, performing soft tissue tensioning which changesloading applied by a medial condyle or a lateral condyle of femur 16 todistractor 10 can result in movement of contact points 44 and 46. Theload magnitude at the point of contact can also be displayed. Thus, thesurgeon can receive the information as the surgical procedure is beingperformed with little or no time penalty but greatly increased knowledgeon the installation. It should be noted that module 32 is configured tobe removed from moving support structure 30. This allows module 32 to beused in another piece of equipment later in the surgery to take furthermeasurements, make adjustments, or verify that the final installationnumbers are similar to that generated when preparing bone surfaces forprosthetic component installation. Similarly, cover 38 can be removedfrom module 32. Cover 38 can be substituted for other covers designed tointerface with a different component. For example, cover 38 isconfigured to interface with the natural condyles of femur 16. Adifferent cover can be used to interface with a prosthetic femoralcomponent coupled to femur 16 later in the surgery to take furthermeasurements or verify the previous quantitative measurement data.

FIG. 3 illustrates cover 38, module 32, and distractor 10 in accordancewith an example embodiment. Moving support structure 30 is shownseparated from frame 36 of fixed support structure 28. Note that movingsupport structure 30 fits within an opening in frame 36 of fixed supportstructure 28 if the distraction distance is reduced by distractionmechanism 24. In one embodiment, moving support structure 30 has a majorsurface 50 configured to support module 32 when loaded by the kneejoint. A surface 58 of module 32 couples to major surface 50 of movingsupport structure 30. In the example, module 32 comprises a medial sideand a lateral side respectively configured to couple to a medial condyleand a lateral condyle of a knee joint. Major surface 50 of movingsupport structure 30 includes at least one alignment feature to retainand align module 32. For example, posts 52 extend from major surface 50of moving support structure 30. Posts 52 are received withincorresponding openings in module 32 when coupling a bottom surface 58 ofmodule 32 to major surface 50 of moving support structure 30. Movingsupport structure 30 can further comprise a wall 56 or walls that alignand retains module 32 to moving support structure 30. Posts 52 and wall56 prevent lateral forces from detaching module 32 from moving supportstructure 30 under knee joint loading. Module 32 can be removed bylifting module 32 vertically from surface 50 of moving support structure30. Module 32 is made to be removable so it can be placed in aprosthetic component such as an insert to make measurements later in thesurgical installation of the knee joint.

Module 32 has electronic circuitry configured to control the measurementprocess and transmit the measurement data. The electronic circuitrycouples to one or more sensors for measuring parameters. In the example,a plurality of load sensors underlies the medial side and the lateralside of module 32. This supports measurement of the load magnitude andthe position of load due to the medial condyle and the lateral condyleof a femur coupled to cover 38. Module 32 is hermetically sealed andincludes a power source such as a battery, super capacitor, inductor, orother structure that can operate module 32 during a surgical procedure.In one embodiment, batteries 60 are used to power the electroniccircuitry in module 32. Module 32 further includes retaining structures54 and 70 extending from a periphery. Retaining structures 54 and 70 areconfigured to align and retain cover 38 to module 32. In the example,cover 38 slidably engages to module 32. In one embodiment, retainingfeature 70 fits into an opening of retaining feature 57 on cover 38 ascover 38 slides across module 32. Retaining feature 57 can flexed andincludes an opening. A force can be applied to cover 38 to flexretaining feature 57 of cover 38 over retaining feature 54 of module 32.Retaining feature 54 of module 32 couples through the opening inretaining feature 57 to retain cover 38 to module 32. Conversely, cover38 can be removed by flexing retaining feature 57 such that retainingfeature 54 of module 32 no longer extends through the opening inretaining feature 57. Cover 38 can then be lifted to separate cover 38from module 32. Cover 38 can then be moved to disengage retainingfeature 70 from the opening of the corresponding retaining feature ofcover 38 (that is not shown) thereby completely separating cover 38 frommodule 32.

A surface 62 and a surface 64 of module 32 is configured to couple tocorresponding interior surfaces of cover 38. The plurality of loadsensors underlie and couple to surface 62 and surface 64 of module 32.The plurality of load sensors are configured to couple to predeterminedlocations of a surface 66 and a surface 68 of cover 38. The plurality ofload sensors measures loading applied by condyles of the femur tosurfaces 66 and 68 of cover 38. The load data from the plurality of loadsensors is used to determine a load magnitude and position of load ofeach condyle to surfaces 62 and 64 in real-time thereby allowingadjustments in-situ.

FIG. 4 illustrates a cover 72 on module 32 configured having ananterior-posterior (A-P) slope of zero in accordance with an exampleembodiment. Cover 72 couples to module 32. Cover 72 is configured tocouple to the natural condyles of a femur. In one embodiment, cover 72is used prior to installation of the femoral prosthetic component and inconjunction with distractor 10 to support making one or more bone cutsto the distal end of a femur for receiving the femoral prostheticcomponent. Module 32 is configured to measure one or more parameters andtransmit measurement data to a computer for further processing. In theexample, disclosed above, module 32 measures loading applied by condylesof a femur on a medial and a lateral side of cover 72.

In one embodiment, a plurality of covers are provided with module 32.The covers can comprise a polymer or metal material. The covers can bemolded to lower cost of manufacture. In one embodiment, the plurality ofcovers provided with module 32 have different anterior-posterior (A-P)slopes. The covers having different A-P slopes are used to change thebiomechanics of the knee joint thereby affecting post-operative clinicaloutcome. Slope can be added to match the posterior tibial slope of theoriginal anatomical condition. Matching the A-P slope supports greaterknee flexion in the posterior cruciate ligament retaining total kneearthroplasty while a lesser slope can be used in a posterior-stabilizedtotal knee arthroplasty. The A-P slope affects the flexion gap, kneejoint stability, and posterior femoral rollback over the range ofmotion. Cover 72 has an anterior-posterior slope of zero degrees. Thus,cover 72 does not add A-P slope for assessment.

FIG. 5 illustrates a cover 74 on the module configured having ananterior-posterior (A-P) slope of 2 degrees in accordance with anexample embodiment. Cover 74 couples to module 32. Cover 74 isconfigured to couple to the natural condyles of a femur. Thus, cover 74is used prior to installation of the femoral prosthetic component and inconjunction with distractor 10. Module 32 is configured to measure oneor more parameters and transmit measurement data to a computer forfurther processing. In the example, module 32 measures loading appliedby condyles of a femur on a medial and a lateral side of cover 74.

In general, a plurality of covers such as cover 74 and cover 72 of FIG.4 are provided with module 32. The covers having different A-P slopesare used to change the biomechanics of the knee joint thereby affectingpostoperative clinical outcome. Slope can be added to match theposterior tibial slope of the original anatomical condition. Matchingthe A-P slope supports greater knee flexion in the posterior cruciateligament retaining total knee arthroplasty while a lesser slope can beused in a posterior-stabilized total knee arthroplasty. The A-P slopeaffects the flexion gap, knee joint stability, and posterior femoralrollback over the range of motion. Cover 74 has an anterior-posteriorslope of +2 degrees for assessing the knee joint with added slope.

FIG. 6 illustrates a cover 76 on the module configured having ananterior-posterior (A-P) slope of 4 degrees in accordance with anexample embodiment. Cover 76 couples to module 32. Cover 76 isconfigured to couple to the natural condyles of a femur. Thus, cover 76is used prior to installation of the femoral prosthetic component and inconjunction with distractor 10. Module 32 is configured to measure oneor more parameters and transmit measurement data to a computer forfurther processing. In the example, module 32 measures loading appliedby condyles of a femur on a medial and a lateral side of cover 76.

In general, a plurality of covers such as cover 76, cover 74 of FIG. 5,and cover 72 of FIG. 4 are provided with module 32. The covers havingdifferent A-P slopes are used to change the biomechanics of the kneejoint thereby affecting postoperative clinical outcome. Slope can beadded to match the posterior tibial slope of the original anatomicalcondition. Matching the A-P slope supports greater knee flexion in theposterior cruciate ligament retaining total knee arthroplasty while alesser slope can be used in a posterior-stabilized total kneearthroplasty. The A-P slope affects the flexion gap, knee jointstability, and posterior femoral rollback over the range of motion.Cover 76 has an anterior-posterior slope of +4 degrees for assessing theknee joint with added slope. FIGS. 4, 5, and 6 are examples and thenumber of covers and A-P slopes can be more or less than shown.

FIG. 7 illustrates a cover 78 on module 32 configured to interface withnatural condyles of a femur in accordance with an example embodiment. Inone embodiment, distractor 10 is inserted in a knee joint with theproximal end of a tibia having a prepared bone surface and the distalend of a femur in a natural state. Natural condyles of the femur coupleto cover 78. Cover 78 will support leg movement over a range of motionwhen the knee joint is distracted. In the example, module 32 measuresloading applied by condyles of a femur on a medial and a lateral side ofcover 78. A plurality of covers identical to cover 78 can be providedeach having different A-P slopes to change the kinematics of the kneejoint. Also, the plurality of covers can comprise different sizes fordifferent knee sizes. For example, the covers can comprise small,medium, and large sizes that accommodate a large statistical sample ofthe population requiring knee joint replacement.

FIG. 8 illustrates a cover 73 on module 32 configured to interface witha femoral prosthetic component coupled to a femur in accordance with anexample embodiment. In one embodiment, distractor 10 is inserted in aknee joint with the proximal end of a tibia having a prepared bonesurface and the distal end of fitted with a femoral prostheticcomponent. Cover 73 is configured to interface with the condyles of thefemoral prosthetic component. In one embodiment, a surface of cover 73has a contour to support leg movement under load with the condyles ofthe femoral prosthetic component coupled to the surface. Cover 73supports all ligaments in place to stabilize the knee joint.

Cover 73 will support leg movement over a range of motion when the kneejoint is distracted. In the example, module 32 measures loading appliedon a medial side and a lateral side by the condyles of the femoralprosthetic component to cover 73. A plurality of covers identical tocover 73 can be provided each having different A-P slopes to change thekinematics of the knee joint. Also, the plurality of covers can comprisedifferent sizes for different knee sizes having different femoralprosthetic component sizes. For example, the covers can comprise small,medium, and large sizes that accommodate a large statistical sample ofthe population requiring knee joint replacement.

FIG. 9 illustrates a cover 77 on module 32 configured to interface witha femoral prosthetic component coupled to a femur in accordance with anexample embodiment. In one embodiment, distractor 10 is inserted in aknee joint with the proximal end of a tibia having a prepared bonesurface and the distal end fitted with a femoral prosthetic component.Cover 77 includes a support structure 79 that provides support when aligament is removed from the knee joint. In one embodiment, supportstructure 79 is coupled to covers disclosed herein above to form cover77. Alternatively, cover 77 can be provided having integral supportstructure 79. Cover 77 is configured to interface with the condyles ofthe femoral prosthetic component. A surface of cover 77 has a contour tosupport leg movement under load with the condyles of the femoralprosthetic component coupled to the surface.

Cover 77 will support leg movement over a range of motion when the kneejoint is distracted and a ligament removed. In the example, module 32measures loading applied on a medial side and a lateral side by thecondyles of the femoral prosthetic component to cover 77. A plurality ofcovers identical to cover 77 can be provided each having different A-Pslopes to change the kinematics of the knee joint. Support structure 79can couple to each of the plurality of covers. Also, the plurality ofcovers can comprise different sizes for different knee sizes havingdifferent femoral prosthetic component sizes. For example, the coverscan comprise small, medium, and large sizes that accommodate a largestatistical sample of the population requiring knee joint replacement.

FIG. 10A illustrates a frame 36 and a frame retaining support structure82 in accordance with an example embodiment. In one embodiment, fixedsupport structure 28 of FIG. 1 comprises retaining support structure 82and frame 36. Frame 36 is configured to be removable from frameretaining support structure 82. Frame retaining support structure 82allows for different frame sizes and different frame shapes to couple todistractor 10. Alternatively, frame 36 and frame retaining supportstructure 82 could be formed as a single structure. In one embodiment,frame retaining support structure 82 is formed as part of housing 20 ofFIG. 1. For example, a portion of housing 20 and frame retaining supportstructure 82 can be made as a single structure or formed in a moldthereby having a fixed geometric relationship between frame retainingsupport structure 82 and a distraction mechanism aligned and retained byhousing 20. Housing 20 can be formed from a polymer material, metal, ormetal alloy that supports loading applied by a knee joint whendistracted. Frame retaining support structure 82 includes retainingstructures 80 configured to retain and align frame 36 to frame retainingsupport structure 82. Frame 36 is coupled to frame retaining supportstructure 82 by pressing frame 36 into frame retaining support structure82 as indicated by arrow 86. Frame 36 includes retaining structures 84that interlock with retaining structures 80 of frame retaining supportstructure 82 such that frame 36 is rigid under loading of the knee jointand does not change a geometric relationship with frame retainingsupport structure 82 or housing 20 of FIG. 1. Conversely, frame 36 canbe removed by applying a force in an opposite direction as arrow 86 toframe 36 to release frame 36 from frame retaining support structure 82.A larger or smaller frame 36 can replace frame 36 that better fits thebone structure of the patient.

FIG. 10B illustrates the frame 36 coupled to frame retaining supportstructure 82 in accordance with an example embodiment. Retainingstructures 84 of frame 36 of FIG. 10A are shown interlocking withretaining structures 80 of frame retaining support structure 82. Frame36 is held in a predetermined position relative to frame retainingsupport structure 82 and the housing of the distractor. In oneembodiment, frame 36 and frame retaining support structure 82 are rigidand do not flex or torque under loading applied by the knee joint.

FIG. 11 illustrates different frame sizes in accordance with an exampleembodiment. Bone size varies across the population of patients requiringknee surgery. Different frame sizes are provided that support a majorityof the total knee arthroplasty surgeries performed each year. A frame 90is shown coupled to frame retaining support structure 82. A larger framecan be used if frame 90 is found to be too small for coupling to theprepared surface of a tibia. Frame 90 would then be removed from frameretaining support structure 82. A frame 92 can then be selected that islarger than frame 90 and installed onto frame retaining supportstructure 82. Thus, the distractor 10 of FIG. 1 supports removableframes and frames of different sizes to couple the distractor to theprepared surface of the tibia 18. The number of frame sizes provided canbe more or less than shown in FIG. 11.

FIG. 12A illustrates moving support structure 30 disengaged from M-Ltilt mechanism 22 in accordance with an example embodiment. M-L tiltmechanism 22 is shown coupling to a portion of distraction mechanism 24.Distraction mechanism 24 comprises a post 106 configured to raise orlower M-L tilt mechanism 22 and moving support structure 30 relative tothe fixed support structure 28 of FIG. 1. A key or handle can beinserted into coupler 104 of M-L tilt mechanism 22. The key when rotatedadjusts an M-L tilt angle of M-L tilt mechanism 22 when engaged. M-Ltilt mechanism 22 further includes a coupler 102 that is configured torotate as the key is rotated.

Moving support structure 30 includes a coupler 100 configured to coupleto coupler 102 of M-L tilt mechanism 22. Coupler 100 is inserted intocoupler 102 thereby retaining and aligning moving support structure 30to M-L distraction mechanism 22. M-L tilt mechanism 22 can be disengagedfrom coupler 102 thereby allowing coupler 102 and moving supportstructure 30 to freely rotate. In one embodiment, coupler 100 has asquare or rectangular shape that fits into a corresponding square orrectangular opening of coupler 102. Couplers 100 or 102 can beconfigured to have a temporary locking mechanism that retains movingsupport structure 30 to M-L tilt mechanism 22 while supportingremovability. Similar to fixed support structure 28, 90, and 92disclosed in FIGS. 10A, 10B, and 11 that are also removable, a pluralityof moving support structures can be provided of different sizes orstyles. In general, two or more moving support structures are providedwith distractor 10 of FIG. 1.

FIG. 12B illustrates moving support structure 30 coupled to M-L tiltmechanism 22 in accordance with an example embodiment. Moving supportstructure 30 as mentioned previously is removable from M-L tiltmechanism 22. This allows other moving support structures of differentsizes or styles to be used with distractor 10 shown FIG. 1. A modulehaving electronic circuitry and at least one sensor is placed on majorsurface 50 of moving support structure 30 to measure at least oneparameter. A cover configured to interface with natural condyles of afemur or a cover configured to interface with a femoral prostheticcomponent couples to the module. Distraction mechanism 24 is configuredto increase or decrease a distraction distance between moving supportstructure 30 and the fixed support structure 28 of FIG. 1. Distractionmechanism 24 raises or lowers both M-L tilt mechanism 22 and movingsupport structure 30. Moving support structure 30 is also configured totilt medially or laterally when M-L tilt mechanism 22 is adjusted. Ingeneral, a plurality of moving support structures are provided. Themoving support structures can comprise different sizes and differentstyles. The different moving support structures can correspond to thedifferent frames disclosed in FIG. 11. The moving support structures canaccommodate the wide diversity and variation of patient bone structurethat is seen in an operating room.

FIG. 13 is an illustration of M-L tilt mechanism 22 in accordance withan example embodiment. In the example, M-L tilt mechanism 22 is a wormgear drive 110. Worm gear drive 110 comprises two or more gears of whichat least one is a worm gear. As shown, worm gear drive 110 comprises aworm gear 112 and a gear 114. A housing 116 at least partially housesworm gear 112 and gear 114. Housing 116 retains, aligns, and supportsrotation of worm gear 112 to gear 114. Coupler 104 couples to worm gear112. In one embodiment, coupler 104 is a shaft of worm gear 112.Typically a key or handle couples to the opening in coupler 104 to allowa user to rotate worm gear 112.

Gear 114 couples to moving support structure 30. Housing 116 retains,aligns, and supports rotation of gear 114 when coupled to worm gear 112.As shown, M-L tilt mechanism 22 is decoupled from adjusting an M-L tiltangle of moving support structure 30. M-L tilt mechanism 22 is decoupledwhen the gear teeth of worm gear 112 are positioned such that the gearteeth of gear 114 do not couple to worm gear 112. Moving supportstructure 30 is free to tilt medially or laterally when M-L tiltmechanism 22 is decoupled and loaded by a knee joint. Gear 114 rotatesas moving support structure 30 rotates and vice versa. The module 32 andcover 38 disclosed in FIG. 2 couple between the condyles of the femurand moving support structure 30. The module 32 is supported by majorsurface 50 of moving support structure 30. Module 32 is aligned andretained to moving support structure 30 by posts 52 and sidewall 56. Themedial or lateral tilt of the knee joint corresponds to the balance ofthe knee joint and alignment of the leg.

In one embodiment, the teeth of worm gear 112 are coupled to the teethof gear 112 to engage M-L tilt mechanism 22 after moving supportstructure 30 has been allowed to freely move to an unequalized M-L tiltangle. The teeth of worm gear 112 are configured to couple to gear 114in a manner where they are self-locking. In other words, worm gear 112and gear 114 hold the position of the moving support structure 30 at theunequalized M-L tilt angle when engaged. The key or handle is insertedinto coupler 104 to rotate worm gear 112. In one embodiment, M-L tiltmechanism 22 is rotated an amount that equalizes the M-L tilt angle.This corresponds to a medial compartment being at an equal in height toa lateral compartment height. Worm gear drive 110 when rotated willchange the medial or lateral tilt depending on the direction of rotationand maintains self-locking at an adjusted medial or lateral tilt.Quantitative measurement data from a sensor is used to determine whenthe M-L tilt angle is equalized. Typically, the loading on the medialand lateral compartments will be unequal. Soft tissue tensioning can beused to adjust the loading applied by the condyles of the femur to thecover of the module. Equalizing the M-L tilt angle reduces an offset ofthe femur to the mechanical axis of the leg.

FIG. 14 is an illustration of distraction mechanism 24 in accordancewith an example embodiment. In one embodiment, distraction mechanism 24comprises a gear drive 132. Gear drive 132 can comprise two or moregears and is configured to increase or decrease separation between fixedsupport structure 28 and moving support structure 30 of distractor 10.Gear drive 132 comprises a post 120 and a gear 122. Post 120 extendsoutside housing 20 and is coupled to moving support structure 30.Housing 20 is configured to align, retain, and support movement of post120 and gear 122. Housing 20 positions gear 122 adjacent to post 120such that teeth of gear 122 engage with gear teeth 126 of post 120. Knob26 couples to gear 122 to facilitate rotation. In one embodiment,housing 20 supports movement of post 120 perpendicular to a plane offixed support structure 28.

Rotating knob 26 rotates gear 122 which in turn raises or lowers post120 depending on the direction of rotation. A spring 128 can be coupledto post 120 and housing 20. Spring 128 can provide a spring resistanceas post 120 is being raised from a minimum distraction distance. Asmentioned previously, the minimum distraction distance corresponds todistractor 10 having support structure 30 within the opening of fixedsupport structure 28. In one embodiment, the minimum distractiondistance occurs when both moving support structure 30 and fixed supportstructure 28 couples to a prepared surface of a tibia. In oneembodiment, a minimum height for a medial compartment and a lateralcompartment of a knee joint occurs when a bottom surface 34 of fixedsupport structure is co-planar with a bottom surface of moving supportstructure 30.

A distraction mechanism lock 124 is configured to prevent movement ofgear drive 132. Distraction lock mechanism 124 is coupled to housing 20and is configured to pivot. Distraction lock mechanism 124 is configuredto be enabled and disabled. A spring 130 supports pivoting ofdistraction lock mechanism 124 in a locked position whereby a tooth ofdistraction lock mechanism 124 is configured to engage with gear 122 toprevent movement. Spring 128 supports retention of the tooth ofdistraction lock mechanism 124 in gear 122 by applying a force on post120 that holds gear 122 against distraction lock mechanism 124 thatprevents a user from rotating knob 26. Moving support structure 30 willmaintain a distraction distance to fixed support structure 28 untildistraction lock mechanism 124 is released or disabled.

FIG. 15 is a block diagram of electronic circuitry 150 in distractor 10of FIG. 1 or module 32 of FIG. 1 in accordance with an exampleembodiment. Components of FIG. 1 may be referred to herein in thediscussion of electronic circuitry 150. Electronic circuitry 150 couplesto sensors 152 in distractor 10 or module 32. Electronic circuitry 150is configured to control a measurement process, receive measurement datafrom sensors 152 and transmit the measurement data to computer 12 ofFIG. 1 for further analysis and feedback. Parameters are measured bysensors 152 coupled to electronic circuitry 150 in module 32 ordistractor 10. Electronic circuitry 150 comprises a power managementcircuit 156, control logic 164, memory 158, and interface circuitry 160.A power source 154 couples to electronic circuitry 150 to power ameasurement process. Electronic circuitry 150 further includes atransceiver 162 and an antenna 174 that can be positioned on or within,or engaged with, or attached or affixed to or within, a wide range ofphysical systems including, but not limited to instruments, equipment,devices, prosthetic components, or other physical systems for use on orin human bodies and configured for sensing and communicating parametersof interest in real time.

In general, electronic circuitry 150 is configured to provide two-waycommunication between distractor 10 or module 32 and computer 12. In oneembodiment, distractor 10 provides quantitative measurement data relatedto a distraction distance, medial-lateral tilt, or anterior-posteriortilt of distractor 10. In one embodiment, module 32 providesquantitative measurement data related to load magnitude, position ofload, position, tilt, balance, and alignment. Alternatively, distractor10 can have mechanical gauges to provide measurement data local to thedevice. The measurement data from distractor 10 or module 32 can be usedby computer 12 in a kinematic assessment to support installation ofprosthetic components to ensure optimal loading, balance, and alignmentthat improves performance and reliability based on clinical evidence.

Power source 154 provides power to electronic circuitry 150 and sensors152. The power source 154 can be temporary or permanent. In oneembodiment, the power source can be rechargeable. Charging of the powersource 154 can comprise wired energy transfer or short-distance wirelessenergy transfer. A charging power source to recharge power source 154can include, but is not limited to, a battery or batteries, analternating current power supply, a radio frequency receiver, anelectromagnetic induction coil, a photoelectric cell or cells, athermocouple or thermocouples, or a transducer energy transfer. Powersource 154 has sufficient energy to operate electronic circuitry 150 indistractor 10 or module 32 for one or more surgeries with a singlecharge. Distractor 10 or module 32 can utilize power managementtechnologies to minimize the power drain of power source 154 while inuse and when it is idling. In one embodiment, distractor 10, module 32,or both can be a disposable device after a surgery is completed.

In one embodiment, power source 154 in distractor 10 or module 32 is arechargeable battery. The rechargeable battery can be recharged by themethods disclosed herein above. Alternatively, power source 154 can be asuper capacitor, an inductor, or other energy storage device. Anexternal charging source can be coupled wirelessly to the rechargeablebattery, capacitor, or inductive energy storage device through anelectromagnetic induction coil by way of inductive charging. Thecharging operation can be controlled by power management circuit 156within electronic circuitry 150. In one embodiment, power managementcircuit 156 supports operation of distractor 10 or module 32 duringcharging thereby allowing the surgery to continue if a low charge onpower source 154 is detected. For example, power can be transferred tothe battery, capacitive energy storage device, or inductive energystorage device by way of efficient step-up and step-down voltageconversion circuitry. This conserves operating power of circuit blocksat a minimum voltage level to support the required level of performance.

Power management circuit 156 is configured to operate under severe powerconstraints. In one embodiment, power management circuit 156 controlspower up, power down, and minimizes power usage. The power managementcircuit 156 can also reduce power during operation of the system. Thepower management circuit 156 can turn off or reduce the power deliveredto circuits that are not being used in a specific operation. Similarly,if the system is idle and not being used, the power management circuit156 can put other unused circuitry in a sleep mode that awakens prior tothe next measurement being made. Power management circuit 156 caninclude one or more voltage regulation circuits that provide a pluralityof different stable voltages to electronic circuitry 150 and sensors 152to minimize power dissipation.

In one configuration, a charging operation of power source 154 canfurther serve to communicate downlink data to electronic circuitry. Forinstance, downlink control data can be modulated onto the energy sourcesignal and thereafter demodulated from an inductor in electroniccircuitry 150. This can serve as a more efficient way for receivingdownlink data instead of configuring an internal transceiver withinelectronic circuitry 150 for both uplink and downlink operation. As oneexample, downlink data can include updated control parameters thatdistractor 10 or module 32 uses when making a measurement, such asexternal positional information or for recalibration purposes. It canalso be used to download a serial number or other identification data.

Control logic 164 controls a measurement process or sequence thatengages the sensors, converts the measurement data into a useableformat, and transmits the information. Control logic 164 can comprisedigital circuitry, a microcontroller, a microprocessor, an ASIC(Application Specific Integrated Circuit), a DSP (Digital SignalProcessing), a gate array implementation, a standard cellimplementation, and other circuitry. Control logic 164 couples to memory158. Memory 158 is configured to store measurement data, softwareroutines, diagnostics/test routines, calibration data, calibrationalgorithms, workflows, and other information or programs. In oneembodiment, one or more sensors may be continuously enabled and controllogic 164 can be configured to receive the measurement data, store themeasurement data in memory, or transmit the measurement data inreal-time. Control logic 164 can include dedicated ports that couple toa sensor to continuously receive measurement data or receive at highsample rates measurement data. Alternatively, control logic 164 canselect a sensor to be measured. For example, multiple sensors can becoupled to control logic 164 via a multiplexer. Control logic 164controls which sensor is coupled through the multiplexer to receivemeasurement data. Multiplexed measurement data works well when themeasurement data is not critical or can be sampled occasionally asneeded. Control logic 164 can also select and receive measurement datafrom different sensors in a sequence. Control logic 164 can beconfigured to monitor the measurement data from a sensor but transmitmeasurement data only when a change occurs in the measurement data.Furthermore, control logic 164 can modify the measurement data prior totransmitting the measurement data to computer 12. For example, themeasurement data can be corrected for non-linearity using calibrationdata.

Interface circuitry 160 couples between sensors 152 and control logic164. Interface circuitry 160 supports conversion of a sensor output to aform that can be received by computer 12. Interface circuitry 160comprises digital circuitry and analog circuitry. The analog circuitrycan include multiplexers, amplifiers, buffers, comparators, filters,passive components, analog to digital converters, and digital to analogconverters to name but a few. In one embodiment interface circuitry 160uses one or more multiplexers to select a sensor for providingmeasurement data to control logic 164. Control logic 164 is configuredto provide control signals that enable the multiplexer to select thesensor for measurement. The multiplexer can be enabled to deliver themeasurement data to control logic 164, memory 158, or to be transmittedin real-time. Typically, at least one analog to digital conversion ordigital to analog conversion of the measurement data occurs via theinterface circuitry 160.

Sensors 152 couple through interface circuitry 160 to control logic 164.Alternatively, interface circuitry 160 can couple directly to circuitryfor transmitting measurement data as it is measured. The physicalparameter or parameters of interest measured by sensors 152 can include,but are not limited to, height, length, width, tilt/slope, position,orientation, load magnitude, force, pressure, contact point location,displacement, density, viscosity, pH, light, color, sound, optical,vascular flow, visual recognition, humidity, alignment, rotation,inertial sensing, turbidity, bone density, fluid viscosity, strain,angular deformity, vibration, torque, elasticity, motion, andtemperature. Often, a measured parameter is used in conjunction withanother measured parameter to make a kinetic and qualitative assessment.In joint reconstruction, portions of the muscular-skeletal system can beprepared to receive prosthetic components. Preparation includes bonecuts or bone shaping to mate with one or more prosthesis. Parameters canbe evaluated relative to orientation, alignment, direction,displacement, or position as well as movement, rotation, or accelerationalong an axis or combination of axes by wireless sensing modules ordevices positioned on or within a body, in an instrument, an appliance,a tool, equipment, prosthesis, or other physical system.

The sensors can directly or indirectly measure a parameter of interest.For example, a load sensor in module 32 of FIG. 1 can comprise acapacitor that has an elastic dielectric that can compress when a loadis applied to the capacitor. This is an indirect form of sensing aparameter (load) where the capacitance of the capacitor varies withloading. The capacitive measurement data is sent to computer 12 of FIG.1 for further processing. Computer 12 can include software andcalibration data related to the elastic capacitors. The load measurementdata can be converted from capacitance values to load measurements. Thecalibration data can be used to curve fit and compensate for non-linearoutput of a sensor over a range of operation. Furthermore, theindividual sensor measurement can be combined to produce othermeasurement data by computer 12. In keeping with the example of loadmeasurement data, the individual load measurement data can be combinedor assessed to determine a location where the load is applied to asurface to which the load sensors couple. The measurement data can bedisplayed on a display that supports a surgeon rapidly assimilating themeasurement data. For example, the calculated measurement data on thelocation of applied load to a surface may have little or no meaning to asurgeon. Conversely, an image of the surface being loaded with a contactpoint displayed on the surface can be rapidly assimilated by the surgeonto determine if there is an issue with the contact point.

In one embodiment, the orthopedic measurement system transmits andreceives information wirelessly. Wireless operation reduces clutterwithin the surgical area, wired distortion, wired disconnect, orlimitations on, measurements caused by the potential for physicalinterference by, or limitations imposed by, cables connecting a devicewith an internal power with data collection, storage, or displayequipment in an operating room environment. Electronic circuitry 150includes wireless communication circuitry 162. In one embodiment,wireless communication circuitry 162 is low power and configured forshort range telemetry. Typically, distractor 10, module 32, and computer12 are located in an operating room such that the transmission ofmeasurement data from distractor 10 or module 32 to computer 12 is lessthan 10 meters. As illustrated, the exemplary communications systemcomprises wireless communication circuitry 162 of distractor 10 ormodule 32 and receiving system wireless communication circuitry 180 ofcomputer 12. The distractor 10 or module 32 wireless communicationscircuitry are inter-operatively coupled to include, but not limited to,the antenna 174, a matching network 172, the telemetry transceiver 170,a CRC circuit 168, a data packetizer 166, and a data input 176. Wirelesscommunication circuitry 162 can include more or less than the number ofcomponents shown and are not limited to those shown or the order of thecomponents.

Similarly, computer 12 includes wireless communication circuitry 180that comprises an antenna 182, a matching network 184, a telemetryreceiver 186, a CRC circuit 188, and a data packetizer 190. Notably,other interface systems can be directly coupled to the data packetizer190 for processing and rendering sensor data. In general, electroniccircuitry 150 couples to sensors 152 and is configured to transmitquantitative measurement data to computer 12 in real-time to process,display, analyze, and provide feedback. In one embodiment, distractor 10includes a magnetic linear sensor configured to measure a distance ofdistraction and a magnetic angle sensor to measure tilt, slope, orangle. Electronic circuitry 150 is coupled to the magnetic linear sensorand the magnetic angle sensor in distractor 10. The distraction distancedata and the M-L tilt measurement data is transmitted by electroniccircuitry 150 in distractor 10 to computer 12 and is displayed ondisplay 14. In one embodiment, module 32 includes a plurality of loadsensor configured to measure load magnitude at predetermined locationsof cover 38 of FIG. 14. Electronic circuitry 150 in module 32 couples tothe plurality of load sensors. Module 32 can further include inertialsensors and other parameter measurement sensors. The measurement datafrom the plurality of load sensors and the inertial sensors istransmitted to computer 12. Computer 12 can further calculate a point ofcontact to the surface of the cover 38 on a medial side and a lateralside. Computer 12 can calculate the load magnitude at the point ofcontact on the medial side or the lateral side. The module can furtheruse the inertial sensors as a position measurement system or a trackingsystem. The tracking data is also sent to computer 12. The results canalso be displayed on display 14 of computer 12. Redundant measurementdata can be generated from distractor 10 and module 32 such as M-L tiltor A-P tilt. The redundant measurement data can be compared to ensureaccuracy of the measurement.

In general, electronic circuitry 150 is operatively coupled to one ormore sensors 152 to control a measurement process and to transmitmeasurement data. Electronic circuitry 150 can be placed near sensors152 or housed with the sensors to simplify coupling to the sensors. Asmentioned previously, electronic circuitry 150 can be placed indistractor 10 and electronic circuitry 150 can be placed in module 32 tocontrol a measurement process and transmit measurement data in eachdevice. Electronic circuitry 150 couples to the magnetic angle sensorand the magnetic distance sensor in distractor 10. Electronic circuitry150 controls a measurement process of the magnetic angle sensor and themagnetic distances sensor of distractor 10 and transmits measurementdata to computer 12. Similarly, electronic circuitry 150 couples tosensors of module 32. Electronic circuitry 150 controls a measurementprocess of the sensors of module 32 and transmits measurement data tocomputer 12. In one embodiment, the process of transmitting data fromdistractor 10 is independent from module 32. Alternatively, theelectronic circuitry 150 of distractor 10 can be in communication withthe electronic circuitry 150 of module 32 to control the measurementprocesses and transmission of measurement data. In one embodiment, thetransmission of the measurement data from different components can besent on different channels or the measurement data can be sent atdifferent times on the same channel.

As mentioned previously, wireless communication circuitry comprises datainput 176, data packetizer 166, CRC circuit 168 telemetry transmitter170, matching network 172, and antenna 174. In general, measurement datafrom sensors 152 is provided to data input 176 of wireless communicationcircuitry 162. The measurement data can be provided from interfacecircuitry 160, from the control logic 164, from memory 158, or fromcontrol logic 164 thru interface circuitry 160 to data input 176. Themeasurement data can be stored in memory 158 prior to being provided todata input 176. The data packetizer 166 assembles the sensor data intopackets; this includes sensor information received or processed bycontrol logic 164. Control logic 164 can comprise specific modules forefficiently performing core signal processing functions of thedistractor 10 or module 32. Control logic 164 provides the furtherbenefit of reducing the form factor to meet dimensional requirements forintegration into distractor 10 or module 32.

The output of data packetizer 166 couples to the input of CRC circuit168. CRC circuit 168 applies error code detection on the packet data.The cyclic redundancy check is based on an algorithm that computes achecksum for a data stream or packet of any length. These checksums canbe used to detect interference or accidental alteration of data duringtransmission. Cyclic redundancy checks are especially good at detectingerrors caused by electrical noise and therefore enable robust protectionagainst improper processing of corrupted data in environments havinghigh levels of electromagnetic activity. The output of CRC circuit 168couples to the input of telemetry transceiver 170. The telemetrytransceiver 170 then transmits the CRC encoded data packet through thematching network 172 by way of the antenna 174. Telemetry transceiver170 can increase a carrier frequency in one or more steps and add theinformation or measurement data from distractor 10 or module 32 to thecarrier frequency. The matching network 172 provides an impedance matchfor achieving optimal communication power efficiency between telemetrytransmitter 170 and antenna 174.

The antenna 174 can be integrated with components of the distractor 10or module 32 to provide the radio frequency transmission. The substratefor the antenna 174 and electrical connections with the electroniccircuitry 150 can further include the matching network. In oneembodiment, the antenna and a portion of the matching network 172 can beformed in the printed circuit board that interconnects the componentthat comprise electronic circuitry 150. This level of integration of theantenna and electronics enables reductions in the size and cost ofwireless equipment. Potential applications may include, but are notlimited to any type musculoskeletal equipment or prosthetic componentswhere a compact antenna can be used. This includes disposable modules ordevices as well as reusable modules or devices and modules or devicesfor long-term use.

The process for receiving wireless communication circuitry 180 is theopposite of the sending process. Antenna 182 receives transmittedmeasurement data from wireless communication circuitry 162. Wirelesscommunication circuitry 162 can transmit at low power such thatreceiving wireless communication circuitry 180 must be in proximity, forexample within an operating room to receive measurement data. Antenna182 couples to matching network 184 that efficiently couples themeasurement data to telemetry transmitter circuit 186. The measurementdata can be sent on a carrier signal that supports wirelesstransmission. The measurement data is stripped off from the carriersignal by telemetry transmitter 186. The measurement data is received byCRC circuit 188 from telemetry transmitter 186. CRC circuit 188 performsa cyclic redundancy check algorithm to verify that the measurement datahas not been corrupted during transmission. The CRC circuit 188 providesthe checked measurement data to data packetizer 190. Data packetizer 190reassembles the measurement data where it is provided to usb interface192. USB interface 192 provides the measurement data to computer 12 forfurther processing. It should be noted that the measuring, transmitting,receiving, and processing of the measurement data can be performed inreal-time for use by a surgeon installing the knee joint.

FIG. 16 is an illustration of a magnetic angle sensor 206 coupled to M-Ltilt mechanism 22 in accordance with an example embodiment. Theillustration includes a magnified view of distractor 10 corresponding toM-L tilt mechanism 22. M-L tilt mechanism 22 couples to moving supportstructure 30 and can adjust the M-L tilt angle of moving supportstructure 30. M-L tilt mechanism 22 can be disengaged from movingsupport structure 30 thereby allowing moving support structure 30 tofreely move medially or laterally. A neutral or 0 degrees medial-lateraltilt occurs when a plane of moving support structure 30 is parallel to aplane of fixed support structure 28. Referring briefly to FIG. 12A acoupler 100 of moving support structure 30 is inserted into a coupler102 of M-L tilt mechanism 22 to retain and align moving supportstructure 30 to M-L tilt mechanism 22. Coupler 102 freely rotates withM-L tilt mechanism 22 when worm gear 112 of FIG. 13 is disengaged.Conversely, the movement of coupler 102 and moving support structure 30are locked into the movement of M-L tilt mechanism 22 when worm gear 112is engaged with gear 114. In other words, M-L tilt mechanism 22 whenengaged can forcibly adjust the M-L tilt angle thereby rotating movingsupport structure 30 and coupler 102 of FIG. 12A medially or laterally.

In one embodiment, magnetic angle sensor 206 comprises a Hall EffectSensor 204 and a magnet 200. The Hall Effect Sensor 204 can be anintegrated circuit that is placed in proximity to magnet 200. Ingeneral, the Hall Effect Sensor 204 comprises an array of sensors thatdetects the perpendicular component of a magnetic field generated bymagnet 200. Each sensor generates a signal and the signals are summedand amplified. In one embodiment, the array of sensors are aligned in acircle. Thus, any rotation of the magnet 200 is detected and the amountof rotation can be calculated. In the example, magnet 200 is coupled tocoupler 102 thereby rotating as coupler 102 rotates. Hall Effect Sensor204 is placed adjacent to magnet 200 and within the magnetic fieldgenerated by magnet 200. Magnetic angle sensor 206 is a sensor thatcouples to electronic circuitry 150 as disclosed in FIG. 15 to storeangle sensor data or transmit angle sensor data in real-time. Arrow 202indicates rotation of magnetic 200 in a clockwise direction when facingdistractor 10. For example, the clockwise direction can correspond to amedial tilt. Magnetic angle sensor 206 can be calibrated to measure zerodegrees when the plane of fixed support structure 28 is parallel withthe plane of moving support structure 30. Hall Effect Sensor 204measures the rotation of magnetic 200 and is calibrated to measure thedegrees of rotation as moving support structure 30 tilts medially. Theangle sensor data is sent to the computer 12 of FIG. 1 and the amount ofmedial tilt is displayed on display 14 of FIG. 1 in real-time.

FIG. 17 is an illustration magnetic angle sensor 206 in distractor 10 inaccordance with an example embodiment. Magnetic angle sensor 206comprises Hall Effect Sensor 204 and magnet 200. In one embodiment,magnet 200 is coupled to and centered on coupler 102 such that magnet200 rotates with coupler 102. Hall Effect Sensor 204 can be mounted on aprinted circuit board 208 that couples to electronic circuitry 150 ofFIG. 15 that can be located in a different area of distractor 10. Aplanar surface of magnet 200 is positioned centrally to a planar surfaceof Hall Effect Sensor 204. As mentioned previously, the Hall EffectSensor 204 is placed within the magnetic field generated by magnet 200.

FIG. 18 is an illustration of moving support structure 30 tiltinglaterally in accordance with an example embodiment. In the example,magnet 200 is coupled to coupler 102 thereby rotating as coupler 102rotates. Hall Effect Sensor 204 is placed adjacent to magnet 200 andwithin the magnetic field generated by magnet 200. The magnetic anglesensor 206 couples to electronic circuitry 150 as disclosed in FIG. 15to receive and transmit magnetic angle sensor data. Arrow 210 indicatesrotation of magnetic 200 in a counter-clockwise direction when facingdistractor 10. For example, the counter-clockwise direction cancorrespond to a lateral tilt. Magnetic angle sensor 206 can becalibrated to measure zero degrees when the plane of fixed supportstructure 28 is parallel with the plane of moving support structure 30.Hall Effect Sensor 204 measures the rotation of magnetic 200 and iscalibrated to measure the degrees of rotation as moving supportstructure 30 tilts laterally as shown. The magnetic angle sensor data issent to the computer 12 of FIG. 1 and the amount of medial tilt isdisplayed on display 14 of FIG. 1 in real-time.

FIG. 19 is an illustration of a magnetic distance sensor 224 indistractor 10 in accordance with an example embodiment. In oneembodiment magnetic distance sensor 224 comprises a magnet 220 and aLinear Hall Sensor 222. The magnetic distance sensor 224 providescontactless position measurement. Magnet 220 is a two pole magnet.Linear Hall Sensor 222 can measure absolute position of lateral movementwhen placed in the magnetic field of magnet 220. The strength of themagnetic field measured by Linear Hall Sensor 222 corresponds todistance but is not linear to distance. Linear Hall Sensor 222 relatesthe non-linear change in magnetic field strength per unit distance andlinearizes the output. Linear Hall Sensor 222 couples to electroniccircuitry 150 of FIG. 15 in distractor 10 where electronic circuit 150is configured to control a measurement process and transmit distractiondistance data.

In one embodiment, Linear Hall Sensor 222 is coupled to a portion ofdistraction mechanism 24 that moves relative to housing 20 and fixedsupport structure 28 of FIG. 14. For example, Linear Hall Sensor 222 cancouple to post 120 of distraction mechanism 24 that increases ordecreases a distraction distance of moving support structure 30 relativeto fixed support structure 28. Operation of distraction mechanism 24 andpost 120 is disclosed in more detail in FIG. 14. Magnet 220 is coupledto housing 20 such that Linear Hall Sensor 222 is in proximity to magnet220. In one embodiment, Linear Hall Sensor 222 and magnet 220 align toan axis to which a distance is measured. In the example, the axis canalign with pole 120. A reference distance can be establishedcorresponding to distractor 10 being at a minimum distraction distancefor the medial and lateral compartment heights with a medial-lateraltilt angle of zero. The reference distance can be displayed on display14 of computer 12 of FIG. 1. As post 120 changes position to increase adistraction distance of distractor 10, Linear Hall Sensor 222 measuresthe magnetic field from magnet 220 whereby the measured magnetic fieldstrength corresponds to distance of Linear Hall Sensor 222 from magnet220. The measured change in height can be added to the referencedistance to arrive at the medial and lateral compartment heights.Electronic circuitry 150 in distractor 10 receives and transmitsdistraction distance data from Linear Hall Sensor 222 to computer 12 ofFIG. 1. Alternatively, Linear Hall Sensor 222 can be placed on housing20 and magnet 220 can be coupled to post 120 such that magnet 220 movesrelative to Linear Hall Sensor 222. In one embodiment, Magnetic distancesensor 224 can be used in conjunction with magnetic angle sensor 206 tocalculate medial or lateral compartment heights. Computer 12 can receivethe height measurement data and the angle measurement data geometricallycalculate the medial height and the lateral compartments heights. In oneembodiment, the medial height and the lateral compartment heights willbe measured at a known position on the medial surface of the module 32and a known position on the lateral surface of module 32.

FIG. 20 is an illustration of display 14 of computer 12 as shown in FIG.1 in accordance with an example embodiment. Electronic circuitry 150 ofFIG. 15 in distractor 10 transmits distraction distance data and M-Ltilt data to computer 12. In a surgical environment reducing patienttime under anesthesia lowers patient risk of complication or death. Asurgeon using quantitative measurement data during orthopedic surgerymust absorb the measurement data rapidly to support installation ofprosthetic components in the shortest possible time. Display 14 of FIG.1 can visualize data in a manner that allows the surgeon to rapidlydetermine if the measurement data verifies the subjective feel of aninstallation or if the installation needs correction and how much.Moreover, display 14 of FIG. 1 supports real-time measurement as acorrection or adjustment is made.

In one embodiment, M-L tilt data is displayed on a meter 230. Meter 230can comprise a first indicator 232 and a second indicator 234.Indicators 232 and 234 comprises opposing pointers that point to agraduated scale on either side of meter 230 corresponding to degrees ofmedial or lateral tilt. This supports at a glance an imbalance or offsetof alignment. Meter 230 can also be used during an equalization step.The equalization step engages M-L tilt mechanism 22 of FIG. 1 toforcibly adjust the M-L tilt to zero. The M-L tilt at zero degreescorresponds to a plane of fixed support structure 28 of FIG. 1 beingparallel to a plane of moving support structure 30 of FIG. 1. The actualquantitative measurement data related to M-L tilt can be displayed withboxes 236, 238, and 240 on display 14.

In one embodiment, distraction distance data is displayed on display 14.Distraction distance corresponds to a distance between a distal end of afemur and a proximal end of a tibia and is displayed visually on display14. A bar chart 250 provides a visual representation of the distractiondistance. Distraction distance values are displayed on one side of thebar graph. A bar in bar chart 250 indicates the distance and is adjacentto the distance values. The distraction distance value can also bedisplay in a box 252 on display 14. A medial or lateral heightrespectively of the medial compartment and the lateral compartment of aknee joint can be calculated by computer 12 and displayed by display 14.

FIG. 21 is an illustration of a top view of module 32 in accordance withan example embodiment. Module 32 includes at least one sensor formeasuring a parameter of the musculoskeletal system. In the example,module 32 includes a plurality of load sensors configured to measure aload applied to a surface 62 and a surface 64 also shown in FIG. 3. Theplurality of load sensors are coupled to predetermined locations ofsurface 62 and 64 that define an area of contact. In one embodiment,each load sensor couples to a vertex of a polygon. As previouslymentioned, cover 38 as shown in FIG. 2 couples to module 32 when placedin distractor 10. Cover 38 couples to surface 62 and 64. Thepredetermined locations of the plurality of load sensors translates tolocations on cover 38 that determine a location of medial or lateralcondyle contact on cover 38.

Module 32 can also be used in trialing the knee joint prior to a finalinstallation of final prosthetic components. For example, a tibialprosthetic component and femoral prosthetic component are installedusing the quantitative measurement data from distractor 10 and module 32as shown in FIG. 1 to determine bone cuts, alignment, and balance. Atrialing insert can then be inserted in the tibial prosthetic to takefurther measurements. The trialing insert can comprise module 32 and acover. The cover is configured to couple to the femoral prostheticcomponent. The combined thickness of module 32 and the cover isdetermined by the bone cuts and measurements made by distractor 10. Inone embodiment, the insert comprising module 32 and the cover isinserted in the tibial prosthetic component. Measurements from module 32as a trialing insert should be similar to the measurements taken withdistractor 10 and module 32. Further adjustments can be made to finetune the prosthetic component installation using quantitativemeasurement data. The trialing insert can then be removed and the finalinsert installed in the knee joint. The final insert should haveloading, position of load, balance, and alignment approximately equal tothat measured using the trialing insert.

FIG. 22 is an illustration of module 32 with a portion of an enclosureremoved in accordance with an example embodiment. Module 32 compriseselectronic circuitry 150 and at least one sensor configured to measure aparameter. Module 32 comprises a first support structure and a secondsupport structure configured to form a housing that is hermeticallysealed. In the example embodiment, a plurality of load sensors 272 areshown on a medial side of module 32. Plurality of load sensors 272 areplaced at predetermined locations in module 32 to support measuring aposition of load applied to the medial side. A load plate that is notshown would overlie plurality of load sensors 272. A plurality of loadsensors are also placed at predetermined locations on a lateral side ofmodule 32 although they cannot be seen in FIG. 22. A load plate 274overlies the plurality of load sensors on the lateral side. Load plate274 distributes loading to a load sensor. In one embodiment, theplurality of load sensors 272 are formed in flexible interconnect 276.Similarly, the plurality of load sensors underlying load plate 274 canbe formed in interconnect 280. The leads of the plurality of loadsensors 272 couple to electronic circuitry 150 as previously disclosedin FIG. 15.

Electronic circuitry 150 can be coupled to a printed circuit board 282.Electronic components can be coupled to, formed in, or interconnected toform a circuit on printed circuit board 282. In one embodiment, leadsfrom plurality of load sensors 272 on flexible interconnect 276 and 280can be coupled to printed circuit board 282 by solder bumping.Electronic circuitry 150 is placed in a region of module 32 that is notsubject to loading by the musculoskeletal system. Electronic circuitry150 controls a measurement process and transmits measurement data fromplurality of load sensors 272. Electronic circuitry 150 receives powerfrom a power source. In one embodiment, the power source comprisesbatteries 270. At least a portion of each battery underlies a portion ofa surface that is loaded by the musculoskeletal system. The battery formfactor is such that compression of module 32 under load by themusculoskeletal system does not touch batteries 270. Batteries 270 arecoupled to electronic circuitry 150 by flexible interconnect 278 and284. Flexible interconnect 278 and 284 can couple to electroniccircuitry 150 by solder bump to printed circuit board 282.

FIG. 23 is an exploded view of an insert 308 prosthetic component inaccordance with an example embodiment. Insert 308 comprises a cover 300and module 32. Distractor 10 of FIG. 1 uses module 32 to support one ormore bone cuts for installation of one or more prosthetic components ofthe knee joint. In general, the load magnitude, position of load,balance, and alignment of the knee joint is measured. The size andheight of the prosthetic components are taken into account in the bonecuts supported by distractor 10. After a tibial bone cut has beencompleted a tibial prosthetic component can be installed in a proximalend of a tibia. The tibial prosthetic component can be a trial tibialprosthetic component or a final tibial prosthetic component. Similarly,a femoral prosthetic component can be installed on a distal end of afemur after the femoral bone cuts on a distal end of the femur are made.

Module 32 comprises a support structure 302 and a support structure 304.Support structures 302 and 304 when coupled together form a housing forat least one sensor, a power source, and electronic circuitry 150. Thehousing is hermetically sealed by welding, adhesive, glue, mechanicalcoupling, blocking channels or other techniques. Support structure 302has a surface 62 and a surface 64 configured to respectively couple toan articular surface 310 and an articular surface 312 of cover 300.Articular surfaces 310 and 312 support movement of the knee joint over arange of motion of the leg. Support structure 304 has a surface 318 thatcouples to a surface of the tibial prosthetic component.

Electronic circuitry 150 is placed in a lightly loaded or unloaded areaof module 32. Electronic circuitry 150 controls a measurement processand transmits measurement data to a computer 12 shown in FIG. 1. Thecomputer 12 is in the operating room and the transmission of themeasurement data is short range. In one embodiment, a first plurality ofload sensors underlie and couple to surface 64 at predeterminedlocations. Similarly, a second plurality of load sensors underlie andcouple to surface 62 at predetermined locations. The predeterminedlocations correspond to vertexes of a polygon that define a measurementregion. Load plates 274 couple between surface 64 and surface 62 ofsupport structure 302 and the first or second plurality of load sensors.Load plates 274 distribute loading applied to surface 260 or surface 262to the first or second plurality of load sensors. A power source couplesto electronic circuitry 150 and the first and second plurality of loadsensors. In one embodiment, the power source comprises batteries 270.Batteries 270 can be single use or rechargeable batteries.

Cover 300 couples to module 32. Module 32 and cover 300 have one or moreretaining features that couple module 32 to cover 300. The retainingfeatures allow cover 300 to be removed from module 32. Cover 300 furtherincludes openings 306 that are configured to receive a handle to directand install insert 308 in the knee joint. In one embodiment, a pluralityof covers can be provided. The plurality of covers each have a differentheight or thickness. The combined thickness of module 32 and a covercorresponds to a height or thickness of a final insert that is installedinto the prosthetic knee joint. The plurality of covers can also includecovers of a different size that support optimal fitting for differentbone sizes. In general, a cover is selected that corresponds to apatient femur and tibia bone size and a thickness corresponding to aspacing between the femoral prosthetic component and the tibialprosthetic component.

Insert 308 is installed in the knee joint. Insert 308 couples to and isretained by the trial or permanent tibial prosthetic component. Cover300 and module 32 have a height or thickness that corresponds to thedistraction distance of the knee joint when using distractor 10 asdisclosed herein above to support prosthetic component installation.Condyles of the femoral component couple to articular surfaces 310 and312 of cover 30. Articular surfaces 310 and 312 of cover 300respectively couple to surfaces 62 and 64 of module 32. The firstplurality of load sensors and the second plurality of load sensorgenerate load measurement data that is sent to from module 32 to thecomputer 12 shown in FIG. 1. Typically, computer 12 is in the operatingroom where the surgeon can review the quantitative measurement datawhile performing the knee joint installation. The predeterminedlocations of the first or second plurality of sensors correspond tolocations on articular surfaces 310 and 312. The computer uses load datafrom the load sensors to calculate a load magnitude and a position ofload where a condyle contacts an articular surface and displays it onthe computer in real-time. The load magnitudes, position of load,balance, and alignment of the knee joint should be similar to themeasurement data using distractor 10 of FIG. 1. Further adjustments orrefinements can be made to change a load magnitude, a position of load,balance, or knee joint alignment. Typically, the adjustment can compriserotating a prosthetic component or applying soft tissue release but boneresection is also an option if the measurement data justifies thechange. The changes in quantitative measurement data can be viewed onthe display as the adjustments are made to ensure optimal jointinstallation. The final insert is then placed in the knee joint. Thefinal knee joint should see load magnitudes, position of load, balance,and alignment equal to insert 308. Thus, module 32 is used in distractor10 of FIG. 1 to generate quantitative measurement data to support one ormore bone cuts prior to installation of at least one prostheticcomponent and module 32 is used in an insert 308 to provide quantitativemeasurement data on the prosthetic knee joint.

FIG. 24 is an anterior view of insert 308 installed on a tibialprosthetic component 320 in accordance with an example embodiment.Insert 308 comprises cover 300 coupled to module 32. In one embodiment,tibial prosthetic component 320 includes a tibial tray 322. The tibialtray 322 is configured to align and retain module 32 to tibialprosthetic component 320. In one embodiment, load data is transmittedfrom insert 308 to the computer 12 shown in FIG. 1.

FIG. 25 is a side view of insert 308 installed on the tibial prostheticcomponent 320 in accordance with an example embodiment. Articularsurface 312 of cover 300 has a curved surface that supports coupling toa condyle of a femoral prosthetic component.

FIG. 26 illustrates a step in a knee joint installation procedure inaccordance with an example embodiment. In general, a bone in a kneejoint is prepared to interface with distractor 10 shown in FIG. 1. Inthe example, a tibia 4020 is selected for resection. A proximal end of atibia is resected and is prepared to receive a tibial prostheticcomponent. In one embodiment, the proximal end of tibia 4020 is cutperpendicular to the tibia anatomical axis using an alignment jig. Forexample, an extramedullary alignment tool can be used align and cut theproximal end of the tibia 40. The resection can also include ananterior-posterior (A-P) slope to the prepared bone surface 404. In oneembodiment an (A-P) slope of 6 degrees slanted posteriorly is made. Thedistal end of femur 400 is left in a natural state.

FIG. 27 illustrates a step of placing distractor 10 in the knee joint ofthe leg in accordance with an example embodiment. A lateral view 412 ofthe leg and a top view of the 410 leg is shown in FIG. 27. In theexample, the leg is placed in extension. The distractor 10 is reduced toa minimum distraction distance and placed on the prepared surface of theproximal end of tibia 402. At the minimum distraction distancedistractor 10 should not require substantial force to fit within theknee joint. Placing distractor 10 at a minimum distraction distance isalso called zeroing distractor 10. A module 32 and a cover 38 is placedon moving support structure 30 as shown in FIG. 1. In one embodiment, abottom surface of both the moving support structure and the fixedsupport structure contact the prepared bone surface of tibia 402.

A M-L tilt lock on distractor 10 is then released. The M-L tilt lockreleases moving support structure 30 as shown in FIG. 13 to freelyswivel medially or laterally. In one embodiment, the moving supportstructure 30 cannot tilt when distractor 10 is at the minimum height. Inone embodiment, the knee joint is not stable with distractor 10 zeroed.The knee joint can be supported to prevent the leg from hyperextendingdue to laxity. The distraction distance of distractor 10 is increaseduntil the knee joint does not require support because the knee jointpressure is sufficient to prevent hyperextension when the leg is raisedby supporting the ankle while observing the knee joint pressure mediallyand laterally. Condyles of the femur couple to cover 38 as shown in FIG.3. Module 32 underlying cover 38 measures loading applied to cover 38and transmits the load data to a computer 12 shown in FIG. 1 for furtherprocessing. Distractor 10 also measures and transmits distractiondistance data and M-L tilt angle data to computer 12 shown in FIG. 1.

FIG. 28 illustrates a step of displaying the distraction distance dataand the M-L tilt angle on a display in real-time in accordance with anexample embodiment. A display 14 couples to the computer 12 receivingdistraction distance data and M-L tilt angle data from distractor 10similar to that shown in FIG. 20. The computer 12 provides the M-L tiltangle data and the distraction distance data on display 14 in real-time.Display 14 shows an M-L tilt meter 420 configured to display the M-Ltilt angle of moving support structure 30 as shown in FIG. 1. M-L tiltmeter 420 comprises an indicator bar 422 that indicates medial andlateral tilt. A surgeon at a glance can determine the amount of M-L tiltand whether the M-L tilt is medial or lateral. The value of the medialtilt angle and the lateral tilt angle can also be seen in boxes 426 and428 on display 14. A tilt angle can also be placed in box 424 forincreased visibility to the surgeon. Alternatively, M-L tilt meter 420can have a graduated scale on either side of M-L tilt meter 420 thatallows indicator bar 422 to point to the medial or lateral tilt anglevalue.

Display 14 also shows a bar graph 430 configured to indicate thedistraction distance of distractor 10. A scale 434 indicates thedistraction distance and is adjacent to bar graph 430. A bar 432 in bargraph 430 indicates the distraction distance but the exact distractiondistance can be read by reading the height of bar 432 from scale 434.The distraction distance can also be read from a box 436. Similar to M-Ltilt meter 420, bar graph 430 allows the surgeon to determine thedistraction distance at a glance. In one embodiment, there will two bargraphs, a first bar graph is a measure of a height of the medialcompartment and a second bar graph is a measure of a height of thelateral compartment of the knee joint. Each bar graph can indicatedistance by graph or numeric value.

FIG. 29 illustrates a step of increasing the distraction distance untila predetermined loading is achieved in accordance with an exampleembodiment. In general, a predetermined loading as disclosed hereinabove and below does not imply a specific load value but a value chosenby a user. The predetermined loading can also be within a range orpredetermined range. For example, the predetermined loading can bewithin a range of 20-40 lbs or 20-60 lbs for a knee joint. It can varygreatly depending on the musculoskeletal system or the joint systemsurgical apparatus 10 is used on. The user of surgical apparatus 10 willselect the predetermined load value a medial or lateral compartment isset at. Similarly, a predetermined height is a height selected by theuser or within a predetermined range set by the user or a componentmanufacturer. An anterior view 440, a side view 442, and a posteriorview 444 of the knee joint is shown in FIG. 29 to illustrate placementof distractor 10. Fixed support structure 28 couples to the preparedbone surface of the proximal end of tibia 402. Module 32 is placed onmoving support structure 30. Cover 38 couples to module 32. The condylesof femur 400 couple to cover 38. The load applied by the condyles offemur 400 to cover 38 is measured by load sensors in module 32 andtransmitted to computer 12 as shown in FIG. 1.

Knob 26 couples to the distraction mechanism in distractor 10. Rotatingknob 26 increases or decreases the distraction distance of distractor10. In one embodiment, knob 26 is rotated to increase the distractiondistance. Increasing the distraction distance will increase the tensionon the ligaments of the knee thereby increasing the loading applied bythe condyles to cover 38 and thereby module 32. In general, module 32measures the loading applied to cover 38 and is displayed on display 14as shown in FIG. 1. The surgeon increases the distraction distance untila predetermined loading is achieved. The predetermined loadingcorresponds to a known value that supports increased performance andreliability of the knee joint. In the example, moving support structure30 has been released to swing freely medially or laterally. Typically,only one side (medial or lateral) will be distracted to thepredetermined loading. The side not at the predetermined loading will beat a lesser value. The distractor 10 is then locked such that movingsupport structure 30 cannot increase or decrease the distractiondistance.

FIG. 30 illustrates a step of reviewing the position of load, the loadmagnitude, M-L tilt angle, and the distraction distance on display 14 asthe distraction distance of distractor 10 is increased in accordancewith an example embodiment. The description will include components ofFIG. 1 and FIG. 29. The quantitative measurement data is sent tocomputer 12 from distractor 10 and module 32. Display 14 includes a topview of cover 38. Circle 456 and circle 458 represent a location wherethe medial and lateral condyles of femur 400 respectively couple to amedial and lateral side of cover 38. Medial load magnitude data isindicated in box 460 and lateral load magnitude data is indicated in box462. As mentioned previously, moving support structure 30 is allowed tofreely rotate in a medial or lateral direction. Knob 26 is rotated untilthe distraction distance of distractor 10 is increased to thepredetermined loading. In the example, the distraction distance is nolonger increased when the lateral side of cover 38 measures 19 pounds atcircle 458. Note that the loading is not balanced and the medial side ofcover 38 measures 15 pounds at circle 460. Distractor 10 is then lockedto prevent movement of moving support structure 30 shown in FIG. 29. Inone embodiment, the predetermined load on the medial and lateral surfaceof cover 38 is in a range from 20 to 40 pounds.

Tilt meter 420 also shows an imbalance related to the M-L tilt angle ofmoving support structure 30 as shown in FIG. 29. Tilt meter 420indicates the lateral side of moving support structure 30 is higher thanthe medial side. The measured M-L tilt angle is indicated in box 424 andcorresponds to an angle between the plane of moving support structure 30and the plane of fixed support structure 28. In the example, box 424indicates an M-L tilt angle of −4.9 degrees. The distraction distance isalso indicated on display 14. Bar graph 434 illustrates the distractiondistance while box 436 provides a value of the distraction distance. Inthe example, box 436 indicates the distraction distance is 13.1millimeters. In one embodiment, the distraction distance is an averagebecause moving support structure 30 has an M-L tilt angle.

The height of the lateral compartment and the height of the medialcompartment can also calculated from the distraction distance data andthe M-L angle data. In one embodiment, the height of the medialcompartment corresponds to a distance from the prepared bone surface ofthe tibia to the point where the medial condyle couples to the medialside of cover 38. Similarly, the height of the lateral compartmentcorresponds to a distance from the prepared bone surface of the tibia tothe point where the lateral condyle couples to the lateral side of cover38. The height of the medial compartment and the height of the lateracompartment take into account the slope of moving support structure 30.The height of the medial compartment is indicated in box 452 and theheight of the lateral compartment is indicated in box 454. In theexample, the medial gap is 11.5 millimeters and the lateral gap is 14.4millimeters. The difference in the height of the medial compartment andthe height of the lateral compartment corresponds to an offset of thefemur relative to the mechanical axis of the leg.

FIG. 31 illustrates a step of reviewing an x-ray of the leg inaccordance with an example embodiment. The x-ray illustrates a femoraloffset relative to the mechanical axis of the leg. Femur 400 is shown inthe x-ray. A line 470 corresponds to a mechanical axis through femur400. The mechanical axis couples through a center of a femoral head 472to a center of the intercondylar notch of a distal end of femur 400. Anoffset or misalignment of femur 400 from the mechanical axis correspondsto line 474. Line 474 is a line drawn from the center of femoral head472 to a center of the ankle.

Typically, the offset of femur 400 is measured prior to or during a kneereplacement surgery. As shown, lines 470 and 474 can be drawn on thex-ray and the offset can be measured with a protractor or other anglemeasurement device. In one embodiment, the angle formed by lines 470 and474 corresponds to the M-L tilt angle measured in FIG. 30. The offsetmeasured in the x-ray is compared against the M-L tilt angle measured bydistractor 10 as seen in FIG. 1. In general, the M-L tilt angle and theoffset angle measured in the x-ray should be approximately equal.

FIG. 32 illustrates an equalizing step where the M-L angle of movingsupport structure 30 is adjusted in accordance with an exampleembodiment. As mentioned previously, distractor 10 is locked such thatmoving support structure 30 cannot increase or decrease the distractiondistance. Also, moving support structure 30 had been allowed to freelyrotate medially or laterally. In one embodiment, the M-L tilt mechanismof distractor 10 can be engaged to moving support structure 30 and isself-locking when changing a M-L tilt angle. A key, handle, or knob iscoupled to the M-L tilt mechanism to change the M-L tilt angle of movingsupport structure 30. In one embodiment, the key is rotated to adjustthe M-L tilt mechanism. Initially, as indicated in FIG. 30, the M-L tiltangle of moving support structure 30 is −4.9 degrees. Femur 400 with theM-L tilt angle of −4.9 degrees corresponds to a position 480. The key isrotated to adjust the M-L tilt mechanism thereby changing the M-L tiltangle from −4.9 degrees to zero degrees. Changing the M-L tilt anglerotates the femur 400 as indicated by arrow 484 until a position 482 isreached. The position 482 is shown without any further movement in FIG.32 where the M-L tilt angle measured by distractor 10 is zero degrees.It should be noted that the loading on the medial and lateral side ofcover 38 of FIG. 29 can change as well as the position of loading on themedial and lateral side.

FIG. 33 illustrates a step of monitoring equalization of femur 400 ofFIG. 32 on display 14 in accordance of an example embodiment. In oneembodiment, the surgeon can monitor display 14 as the key is rotated onthe M-L tilt mechanism. The surgeon rotates the key until M-L tilt angleis zero. This also corresponds to the condition where the plane of fixedsupport structure 28 of FIG. 32 and the plane of moving supportstructure 30 are parallel to one another. Note that the averagedistraction distance as indicated in box 436 does not change. The medialgap as indicated in box 452 and the lateral gap as indicated by box 454does change because the M-L tilt has changed to zero. The medial gapindicated in box 452 reads 12.9 millimeters and the lateral gapindicated in box 454 reads 13.2. Referring briefly to FIG. 31, the stepof equalizing moves the center of the femoral head 472 medially as shownin FIG. 32. Note on FIG. 31 that moving the center of the femoral head427 medially reduces the offset angle formed by lines 470 and 474thereby placing the leg in better alignment. In general, the step ofequalizing eliminates or reduces the offset of the femur 400 to anacceptable alignment based on clinical evidence.

FIG. 34 illustrates a step of drilling guide holes in femur 400 inaccordance with an example embodiment. As disclosed in FIG. 32 and FIG.33, distractor 10 the height of the medial compartment and the height ofthe lateral compartment have been made equal. Equalizing the medial andlateral compartment heights eliminates or reduces the femoral offsetrelative to the mechanical axis of the leg such that the leg is inalignment. Moving support structure 30 has been locked to preventmovement or change of the distraction distance. The medial compartmentheight and the lateral compartment height having an M-L tilt angle ofzero is also locked in place. In one embodiment, the M-L tilt mechanismis self-locking. The knob coupled to the M-L tilt mechanism has beenremoved so the M-L tilt angle cannot be changed. Adjustments to changethe applied loading to the medial or lateral surface of cover 38 areperformed prior to drilling guide holes. For example, soft tissuerelease can be performed to adjust the load values.

Femur 400 is in alignment with the mechanical axis having the height ofthe medial compartment equal to the height of the lateral compartment.The load and position of load on the medial side and the lateral side ofcover 38 have been quantitatively measured and verified withinacceptable predetermined ranges for the prosthetic knee joint system.The measured distraction height relates to a thickness of an installedfinal tibial prosthetic component, a final insert, and a final femoralprosthetic component. Thus, femur 400 guide pin holes can be drilled toalign and support a resection guide for the distal end of femur 400. Adrill guide holder 490 is coupled to distractor 10. A drill guide 492couples to drill guide holder 490. Drill guide holder 490 aligns andretains drill guide 492 adjacent to the distal end of femur 400. Drillguide 492 includes one or more openings 496 that receive a drill bit 494to drill openings in the distal end of femur 400.

FIG. 35 illustrates a step of removing drill guide 492 and drill guideholder 490 of FIG. 34 from distractor 10 in accordance with an exampleembodiment. Holes 500 are drilled using drill guide holder 490 and drillguide 492 coupled to distractor 10 as shown in FIG. 34. Holes 500 willsubsequently be used to couple a resection guide to femur 500 and makeone or more cuts for fitting a femoral prosthetic component to thedistal end of femur 400.

FIG. 36 illustrates a step of reducing the distraction distance ofdistractor 10 and placing the leg in flexion in accordance with anexample embodiment. The M-L tilt mechanism is released allowing movingsupport structure 30 to freely swing medially or laterally. Distractor10 is adjusted to a minimum distraction distance. In one embodiment, theminimum distraction distance occurs when both fixed support structure 28and moving support structure 30 couple to the prepared surface at theproximal end of tibia 402. As mentioned previously, the plane of fixedsupport structure 28 corresponds to zero degrees M-L tilt. In oneembodiment, the minimum distraction distance is 6.8 millimeters. The legcan be placed in flexion where tibia 402 and femur 400 form a 90 degreeangle. In one embodiment, module 32 includes an inertial sensorconfigured to measure the angle between femur 400 and tibia 402. Theinertial sensor data is transmitted to the computer and can be displayedon display 14.

Display 14 is shown with tilt meter 420 and bar graph 430. Tilt meter420 indicates an M-L tilt angle of zero degrees. Since moving supportstructure 30 can swing freely medially or laterally it couples to theprepared surface of tibia 402 with fixed support structure 28. Thus,both are coupled to the same plane and the M-L tilt angle is zerodegrees. The M-L tilt mechanism was enabled in FIG. 32 and adjusted toequalize the medial and lateral gap such that the M-L tilt angle iszero. The M-L tilt angle of 0.0 degrees is indicated in box 424. The bargraph 430 indicates a minimum distraction distance on bar 432. Theminimum distraction distance of 6.8 millimeters is shown in box 436.

FIG. 37 illustrates a step of adjusting the distraction distance whilethe leg is in flexion in accordance with an example embodiment. The stepof adjusting the distraction distance is similar to when the leg was inextension. Distractor 10 of FIG. 36 is adjusted to increase thedistraction distance from the minimum distraction distance. The loadingon the medial and lateral sides of cover 38 of FIG. 36 will increase asthe distraction distance increases. In one embodiment, the surgeon isviewing the load magnitude on display 14 as the distraction distance isincreased. This is indicated in box 460 and box 462 on display 14showing the position of load on the medial and lateral surface of cover38. The distraction distance is increased until the loading on cover 38reaches a predetermined value. Note that the values on the medial andlateral sides of cover 38 are not equal under flexion but the maximumload value corresponds to the desired predetermined value.

The moving support structure of FIG. 36 was released from the M-L tiltmechanism to allow it to freely swing medially or laterally when inflexion. M-L tilt meter 420 indicates the M-L tilt angle and the valueis displayed in box 424 as −4.9 degrees. The distraction distance isalso displayed in bar graph 430 and the value of 13.1 millimeters isdisplayed in box 436. The distraction distance is an average distance.The height of the medial compartment and the height of the lateralcompartment is calculated by computer 12 of FIG. 1 using the measurementdata such as the M-L tilt angle, the position of load, and distractiondistance. The height of the medial compartment is measured as 11.5millimeters as shown in box 452 of display 14. The height of the lateralcompartment is measured as 14.4 millimeters as shown in box 454 ofdisplay 14. The measurement data listed herein above can be stored inmemory of computer 12 shown in FIG. 1.

FIG. 38 illustrates a step of equalizing the height of the medialcompartment and the height of the lateral compartment with the leg inflexion in accordance with an example embodiment. The distractionmechanism is locked to prevent movement of moving support structure 30of FIG. 36. The M-L tilt mechanism is engaged to adjust the M-L tiltangle of moving support structure 30. As mentioned previously, M-L tiltmechanism is self-locking. The M-L tilt angle is adjusted to equalizethe M-L tilt angle to zero degrees with the leg in flexion. Adjustingthe M-L tilt angle to zero degrees equalizes the height of the medialand lateral compartments with the leg in flexion. Similar to FIG. 31 anoffset of the leg alignment in flexion is reduced when the medial gapand the lateral gap equalized. The loading on the medial and lateralsides of cover 38 is viewed on display 14 and adjusted if the loading istoo high or the balance is significantly off. Typically, soft tissuerelease is used to adjust the loading and balance.

After adjustments have been made under equalized conditions thedistraction mechanism lock is released and the M-L tilt mechanism isdisengaged to allow moving support structure 30 to freely rotatemedially and laterally. Measurement data should indicate that the medialand lateral gap are closer than was previously measured in flexion. Themeasurement data should also indicate the medial and lateral sides arein better balance and the load magnitude is within a predetermined rangethat supports performance and reliability of the knee joint. In theexample, the medial gap is listed in box 452 as 11.5 millimeters. Thelateral gap is listed in box 454 as 12.7 millimeters. The differencebetween the applied load between the medial and lateral sides is 1 lband the highest load magnitude is 15 lbs on the lateral side of cover38. The difference in the gap height between the knee joint in extensionand the knee joint in flexion can be due to knee geometry or position ofapplied load on cover 38. The gap data, load data, balance data, and M-Ltilt angle is stored in memory on computer 12 as shown in FIG. 1. Itshould be noted that the values disclosed herein above for the knee inextension and flexion can vary significantly from the data disclosed andis only used as an example.

FIG. 39 illustrates a step of placing a sizer 510 on distractor 10 tosupport selection of a femoral prosthetic component in accordance withan example embodiment. Selecting a correct size for the femoralprosthetic component minimizes overhang of the femoral prostheticcomponent, minimizes bone resection, and maximize coverage usingalgorithms to determine an optimal installation for different models ofthe femoral prosthetic component. Previously, the leg was equalized andadjusted in flexion using quantitative measurement information frommodule 32 and distractor 10 as shown in FIG. 36. A sizer 510 isconfigured to couple to distractor 10 with the leg in flexion. In theexample embodiment, tibia 402 is at approximately a 90 degree angle tofemur 400. The exact angle can be quantitatively measured with aninertial sensor in module 32. Sizer 510 comprises a fork 520, a femurcoupler, a threaded cylinder 518, a spring 512, a knob 516, and a scale514. Fork 520 includes one or more retaining features that align andretain fork 520 to distractor 10. Threaded cylinder 518 extends fromfork 520 above femur 400 in flexion. Spring 512 overlies threadedcylinder 518 and is supported by fork 520. The femur coupler couples tothe threaded cylinder 518 and femur 400. In one embodiment, threadedcylinder 518 couples through an opening of the femur coupler such that aportion of the femur coupler is supported by spring 512. The femurcoupler also couples to a location on femur 400. Knob 516 threads ontothreaded cylinder 518 and couples to the femur coupler. Spring 512provides resistance against the femur coupler and knob 516. Scale 514 isformed on threaded cylinder 518 and is visible above a top surface ofknob 516. Scale 514 is used to select a femoral prosthetic componentsize.

FIG. 40 illustrates a step of coupling a femur coupler 521 to femur 400with the leg in flexion in accordance with an example embodiment. Femurcoupler 521 comprises a body 522 and an extension 524. Body 522 extendsfemur coupler 521 from threaded cylinder 518 over femur 400. Extension524 extends from body 522 and couples to femur 400. In one embodiment,extension 524 includes at least one bend that supports coupling to femur400 without body 522 coupling to femur 400. Extension 524 can couple toa predetermined location on femur 400 or a bone landmark of femur 400.As mentioned previously scale 514 can be read above a surface of knob514 to support selection of the femoral prosthetic component.

FIG. 41 illustrates a step of providing a plurality of sizers 550 tosupport selection of the femoral prosthetic component. In oneembodiment, four different sizers are provided to select the femoralprosthetic component that best fits the knee joint. A sizer 530 islabeled SY and includes a scale 540. A sizer 532 is labeled BM andincludes a scale 542. A sizer 534 is labeled SN and includes a scale544. A sizer 536 is labeled ZM and includes a scale 546. The scales 540,542, 544, and 546 are all different and support selection of the femoralprosthetic component. Sizers 530, 532, 534, and 536 can have one or moredrill guide holes configured to support drilling holes in the distal endof the femur 400.

FIG. 42 illustrates a step of drilling one or more holes in the distalend of femur 400 in flexion in accordance with an example embodiment.The one or more holes will be used to align or support a cutting guideconfigured to prepare a surface of the femur 400. The leg is in flexionhaving femur 400 and tibia 402 at approximately a 90 degree angle.Distractor 10 has been used to equalize the knee joint, align the leg,and the load magnitudes have been adjusted if needed. A sizer 510 hasbeen selected as providing the best fit for femur 400. Sizer 510 has oneor more drill guides 550 for receiving a drill bit 552 to drill femur400. A drill using drill bit 552 is used to drill a hole in femur 400using drill guide 550.

FIG. 43 illustrates one or more holes drilled in the distal end of thefemur in accordance with an example embodiment. Holes 554 are drilled inthe distal end of the femur to support the cutting guide for preparing abone surface of the femur 400 for receiving the femoral prostheticcomponent. Distractor 10 and sizer 510 of FIG. 42 were used to drillholes 554 at predetermined locations. The distractor 10 is removed fromthe knee joint.

Bone surfaces of the distal end of femur 400 are prepared and thefemoral prosthetic component is installed. Similarly, the tibialprosthetic component can be installed. Module 32 can be installed in aninsert 308 as disclosed in FIG. 24 and FIG. 25. Insert 308 can beinstalled in the knee joint such that insert 308 is coupled to andretained by the tibial prosthetic component. The knee joint can be movedthrough a range of motion for the surgeon to gain subjective feedback onthe knee joint installation. Module 32 will send quantitativemeasurement data to the computer 12 as shown in FIG. 1 for furtherevaluation. In general, module 32 should provide similar measurementdata as generated in flexion and extension using distractor 10. In oneembodiment, computer 12 checks the measurement data from insert 308 andcompare it to the previously measured data using distractor 10. Thus,module 32 and insert 308 can be used to verify proper installation ofthe knee joint. Moreover, fine adjustments can be made to furtherimprove the joint installation prior to finalizing the installation. Theinsert 308 is then removed and a final insert equal in size is insertedto complete the knee joint installation.

FIG. 44 is an illustration of a distractor 1000 in accordance with anexample embodiment. Referring briefly to FIG. 1 distractor 10 isconfigured to distract a knee joint, transmit measurement data to aremote system such as a computer 12, and display the measurement data inreal-time on display 14 in an operating room. Distractor 1000 is analternate embodiment of distractor 10. Distractor 1000 can be usedsimilarly to distractor 10 as disclosed herein above. Distractor 1000can include one or more sensors to measure distraction height,medial-lateral angle, load magnitude applied by the musculoskeletalsystem to the distractor, leg position, support one or more bone cuts,support alignment, and measure position of load applied to the medialand lateral surfaces of the distractor.

Referring back to FIG. 44, the distractor 1000 comprises a housing 600,a fixed plate 602, lateral plate 604 (for a knee joint of a left leg), amedial plate 606 (for the knee joint of the left leg), a lateral brake608, a medial brake 610, a knob 616, a lateral height scale 614, and amedial height scale 612. Knob 616 is used to raise and lower lateralplate 604 and medial plate 606 in relation to fixed plate 602. Fixedplate 602 couples to a prepared surface of a tibia. In one embodiment,knob 616 is rotated counter clockwise or clockwise to raise or lowerplates 604 and 606. The amount of lateral distraction and medialdistraction can be respectively read off of lateral scale 614 and medialscale 612 on housing 600. One or more magnetic height sensors can beused to measure the lateral and medial distraction heights as disclosedherein above. The electronic circuitry as disclosed in FIG. 15 iscoupled to the one or more magnetic height sensors and placed withinhousing 600 to control a measurement process and transmit the heightdata to be displayed on a display within the operating room. Distractor1000 can be used in a knee joint of the right leg with the knowledgethat the medial and lateral sides of distractor 1000 are transposed.Alternatively, a second distractor could be provided for a right leg.Note that distractor 1000 has plates 604 and 606 offset. The offsetsupports placement of the patella on a lateral side of the knee jointand allows the patella to be placed back on the knee joint afterdistractor 1000 is inserted. The patella loads the knee joint which istaken into account in all the measurement data and subsequent stepstaken prior to the knee joint installation. The second or right legdistractor provided with distractor 1000 would have an opposite offsetto support placement of the patella laterally on the right knee jointprior to installation of the second distractor.

Distractor 1000 is configured to distract, equalize, and supportalignment of a leg to the mechanical axis of the leg by one or more bonecuts to the femur. The bone cuts to a distal end of the femur supportinstallation of a femoral prosthetic component that aligns the femur andtibia to the mechanical axis. Distractor 1000 is used to drill guideholes for a cutting jig with the leg in extension and flexion. Thecutting jig is then coupled to the distal end using the guide holes andthe bone cuts are made. In general, distractor 1000 is configured togenerate an offset on the prepared surfaces of the distal end of thefemur that reduces or eliminates a varus or vargus leg deformity thatsupports an installation of a prosthetic knee joint in alignment to themechanical axis of the leg.

FIG. 45 is an illustration of the distractor 1000 with a transparenthousing to illustrate components therein in accordance with an exampleembodiment. Knob 616 is configured to rotate to raise and lower slideblock 620. In one embodiment, a threaded shaft extends from knob 616.The threaded shaft is aligned and retained by a structure 626 formed inhousing 600. In one embodiment, structure 626 can have an opening with abearing surface. The threaded shaft can have a region that is notthreaded that couples to the bearing surface of structure 626 to supportalignment of the threaded shaft within housing 600 and rotation of thethreaded shaft. Alternatively, structure 626 can have a threaded openingfor receiving the threaded shaft. Slide block 620 includes a threadedopening configured for receiving the threaded shaft coupled to knob 616.In one embodiment, slide block 620 is not fastened to housing 600whereas structure 626 is attached or integrated as part of housing 600.Thus, rotating knob 616 can raise or lower slide block 620 in relationto structure 626 but only slide block 620 can move in relation tohousing 600.

Slide block 620 is housed within housing 600 and includes a free wheelgear 618. In one embodiment, free wheel gear 618 is located at aproximal end of slide block 620 and configured to rotate. A post 622extends from lateral plate 604 and is configured to move parallel toslide block 620 and the threaded shaft. Post 624 has gear teeth engagingwith free wheel gear 618. Similarly, a post 624 extends from medialplate 606 and is configured to move parallel to slide block 620 and thethreaded shaft. Post 622 has gear teeth engaging with free wheel gear618. Posts 622 and 624 extend through openings in a proximal end ofhousing 600 into an interior of the housing. Housing 600 aligns,retains, and supports movement of lateral plate 606 and medial plate604. In one embodiment, grooves are formed in posts 622 and 624. Housing600 has corresponding tongues 628 that fit within the grooves that alignand retain post 622 and post 624 to the housing. Tongues 628 extendingfrom an interior surface of housing 600 are received within the groovesof posts 622 and 624 and are configured to support movement parallel tothe threaded shaft and slide block 620.

In the illustration, knob 616 cannot be rotated clockwise as slide block620 contacts structure 626 whereby no gap exists to allow furtherrotation or the threaded shaft. In this position, lateral plate 606 andmedial plate 604 are in a minimum height position corresponding tolateral plate 606 and medial plate 604 contacting fixed plate 602. Fixedplate 602 is coupled to housing 600. In one embodiment, fixed plate 602extends from housing 600 and is molded or machined as part of housing602. Fixed plate 602 can be at a 90 degree angle relative to themovement of post 622, post 624, slide block 620, and the threaded shaft.

Brakes 608 and 610 respectively prevent movement of post 622 and post624. In one embodiment, brakes 608 and 610 are friction brakes. Brakes608 or 610 can include a threaded shaft 632. The threaded shaft 632 ofbrakes 608 or 610 couples through a threaded opening 630 formed inhousing 600. Rotating threaded shaft 632 in opening 630 clockwise orcounter clockwise can respectively increase or decrease the depth ofthreaded shaft 632 within housing 600. In one embodiment, threaded shaft632 of brake 608 contacts and applies pressure to post 622 as brake 608is rotated clockwise. The pressure applied to post 622 presses tongues628 against the corresponding grooves on post 622. The friction createdbetween tongues 628 and post 622 by brake 608 prevents movement of post622 and thereby lateral plate 604. Similarly, threaded shaft 632 ofbrake 610 can be rotated to contacts and apply pressure to post 624 asbrake 610 is rotated clockwise. The pressure applied to post 624 pressestongues 628 against the corresponding grooves on post 624. The frictioncreated between tongues 628 and post 624 by brake 610 prevents movementof post 624 and thereby medial plate 606. Conversely, rotating brakes608 and 610 counter-clockwise where brakes 608 and 610 do notrespectively contact posts 622 and 624 allows posts 622 and 624 to movewithout friction.

FIG. 46 illustrates a step in a knee joint installation procedurerelated to distractor 1000 shown in FIG. 44 in accordance with anexample embodiment. The listing of the steps herein below does not implyany order or sequence. Distractor 1000 is placed in the knee jointsimilar to that shown in FIG. 1. A proximal end of the tibia has aprepared surface and the leg is positioned in extension. The fixedposition plate 602 couples to the prepared surface of tibia. Theproximal end of tibia can be cut perpendicular to the tibia anatomicalaxis using an alignment jig. The resection of tibia can also include ananterior-posterior (A-P) slope.

A computer receives transmitted measurement data from distractor 1000.Referring back to FIG. 46 load sensors (not shown) can be embedded inmedial plate 606 and lateral plate 604 to support measurement of a loadmagnitude and position of load applied to plates 604 and 606.Alternatively, the load sensors can comprise a module that rests on asurface of medial plate 604 or lateral plate 606. Distractor 1000 canalso include one or more magnetic sensors configured to measure adistraction distance between lateral plate 604 and fixed plate 602 asdisclosed herein above. The one or more magnetic sensors can also beconfigured to measure a distraction distance between medial plate 606and fixed position plate 602. The distraction distance data and the loadmeasurement data is transmitted to the computer for further processing.In one embodiment, the load sensors and the one or more magnetic heightsensors couple to electronic circuitry such as shown in FIG. 15. Theelectronic circuitry of FIG. 15 is configured to control a measurementprocess and transmit measurement. The electronic circuitry and the oneor more magnetic height sensors can be housed in housing 600 ofdistractor 1000. The load measurement data received by the computer canbe used to calculate the load magnitude and the position of load appliedto lateral plate 604 and medial plate 606. The load magnitude and theposition of load can be displayed on a display coupled to the computerin real-time to the surgeon in the operating room. Similarly, thedistraction height measurement data related to the lateral plate 604 andthe medial plate 606 received by the computer can be displayed on thedisplay. The distraction height measurement data can also be used tocalculate a medial-lateral slope between lateral plate 604 and medialplate 606. The slope would correspond to a line through contact point(e.g. position of load) on the lateral plate 604 and the medial plate606.

In the illustration, distractor 1000 is placed in the knee joint. Thenatural femur 700 is shown having a medial condyle 704 and a lateralcondyle 702 respectively overlying the lateral plate 604 and the medialplate 606. Distractor 1000 is inserted in a minimum distraction height.As mentioned previously, the minimum distraction height corresponds tothe lateral plate 604 and the medial plate 606 coupling to the fixedposition plate 602. Brakes 608 and 610 are not enabled for respectivelypreventing movement of lateral plate 604 and medial plate 606.

FIG. 47 illustrates a step in the knee joint installation procedurerelated to distractor 1000 wherein knob 616 is rotated counter clockwisein accordance with an example embodiment. The direction of rotation ofknob 616 is indicated by arrow 706. Rotating knob 616 counter clockwiserotates threaded shaft 710 such that slide block 620 moves away fromstructure 626. In the example, lateral plate 604 and medial plate 606are unloaded and posts 622 and 624 are free to move. Slide block 620moves in a direction indicated by arrow 708. In the unloaded state,slide block 620 moves both lateral plate 606 and medial plate 604equally in the direction indicated by arrow 708. A distraction heightcorresponds to the separation between lateral plate 604 or medial plate606 and fixed position plate 602. The distraction height is indicated bydouble sided arrow 712 and is labeled H. As mentioned, medial plate 606is raised simultaneously with lateral plate 604 and by an equal amountfrom fixed position plate 602. The distraction data from magneticdistance sensor can be transmitted to the computer and the distractiondistance H can be displayed on the display of the computer within theoperating room to review the distraction distance in real-time. Notethat the lateral condyle 702 and the medial condyle 704 are not incontact with lateral plate 604 or medial plate 606.

FIG. 48 illustrates a step in the knee joint installation procedurerelated to distractor 1000 coupling to femur 700 in accordance with anexample embodiment. As mentioned previously, fixed position plate 602rests against a prepared surface of a tibia (not shown). Brakes 608 and610 are not enabled thereby allowing posts 622 and 624 to move freely.Knob 616 rotates threaded shaft 710 counter clockwise to increase a gapbetween slide block 620 and structure 624 as indicated by arrow 708.Slide block 620, post 622, and post 624 are motivated by threaded shaft710 to raise lateral plate 604 and medial plate 606 thereby increasing adistraction height as indicated by double sided arrow 712. Lateral plate604 and medial plate 606 move simultaneously and by the same amount. Inthe example, lateral condyle 702 contacts lateral plate 604. In oneembodiment, load sensors coupled to lateral plate 604 would register ameasureable load as lateral condyle 702 couples to lateral plate 604.The load measurement data can be displayed on the display coupled to thecomputer receiving the load measurement data. Note that medial plate 606is not in contact with medial condyle 704. In one embodiment, thecounter clockwise rotation of knob 616 continues until a predeterminedload magnitude is reached applied by lateral condyle 702 to lateralplate 604. As mentioned, the change in load magnitude can be viewed onthe display in real-time. Typically, the predetermined load magnitudecan be within a predetermined load magnitude range that has beenclinically proven to provide performance, reliability, and longevity ofthe prosthetic knee joint.

FIG. 49 illustrates the step in a knee joint installation procedurerelated to distractor 1000 where lateral plate 604 and medial plate 606contact femur 700 in accordance with an example embodiment. Aspreviously stated, the lateral plate 604 is in contact with lateralcondyle 702 and distracted to a predetermined load magnitude. Thelateral plate 604 measuring the predetermined load magnitude alsocorresponds to a predetermined distraction distance. Brake 608 isrotated clockwise to contact post 622 to prevent any further movement oflateral plate 604. Brake 610 is not enabled and post 624 is free to moveas slide block 620 moves.

Knob 616 is rotated counter clockwise to increase the gap between slideblock 620 and structure 626. Brake 608 prevents post 622 from moving butfree wheel gear 618 rotates clockwise as threaded shaft 710 is rotatedcounter clockwise. Free wheel gear 618 engages with the gear teeth ofpost 624 as it rotates clockwise. The clockwise rotation of free wheelgear 618 increases the distraction distance between medial plate 606 andfixed position plate 602. Thus, lateral plate 604 does not move whilethe distraction distance between medial lateral plate 606 and fixedposition plate 602 increases until medial lateral plate 606 contactsmedial lateral condyle 704 of femur 700. Similar to lateral plate 604,load sensors coupled to medial plate 606 would register a measureableload as medial condyle 704 contacts medial plate 606. Loading andposition of load on medial plate 606 is displayed on the display coupledto the computer receiving the load measurement data. In one embodiment,knob 616 is rotated counter clockwise to increase the load magnitudeapplied to medial plate 606 until it is equal to the load magnitudeapplied to lateral plate 604 (e.g. the predetermined load magnitude).Thus, the tension of medial collateral ligament is the same as thelateral collateral ligament.

FIG. 50 illustrates a step in the knee joint installation procedurerelated to distractor 1000 where equalization of the medial gap and thelateral gap occurs in accordance with an example embodiment. In general,the medial gap is the distraction distance in the medial compartment ofthe knee joint. Similarly, the lateral gap is the distraction distancein lateral compartment of the knee joint. Referring briefly to FIG. 49,the medial gap is larger than the lateral gap but both are set such thatthe tension of the medial collateral ligament is the same as the lateralcollateral ligament.

Referring back to FIG. 50, brake 610 is enabled to prevent movement ofpost 624. Conversely, brake 608 is released whereby post 622 can movefreely to increase or decrease the distraction distance between lateralplate 604 and fixed position plate 602. In the example, the lateral gapis smaller than the medial gap. Thus, a process of equalizing the medialand lateral gaps corresponds to increasing the lateral gap. Knob 616 isrotated counter clockwise as indicated by arrow 706. Knob 616 rotatesthreaded shaft 710 counter clockwise to increase the distance betweenslide block 620 and structure 626. Free wheel gear 618 rotates counterclockwise by engagement with the gear teeth of post 624 in a fixedposition (e.g. locked by brake 610) as slide block 620 moves asindicated by arrow 708. The counter clockwise rotation of free wheelgear 618 moves post 622 in a direction indicated by arrow 714 as thegear teeth of post 622 engages with free wheel gear 618. As mentioned,brake 608 is disabled allowing post 622 to move as free wheel gear 618rotates.

The distraction distance between lateral plate 604 and fixed positionplate 602 is increased until the lateral gap is the same as the medialgap. Increasing the medial gap increases the tension on the medialcollateral ligament. Conversely, the tension on the medial collateralligament is not raised significantly because medial plate 606 does notmove. In one embodiment, soft tissue release can be practiced on thelateral collateral ligament to reduce the tension and equalize thetensions between the medial collateral ligament and the lateralcollateral ligament. Load sensors coupled to medial plate 606 andlateral plate 604 provide load measurement data to the computer wherebythe load magnitude data applied to medial plate 606 and lateral plate604 can be viewed in real-time. Thus, the soft tissue release can beperformed until the load magnitude on medial plate 606 and the lateralplate 604 are the same which corresponds to approximately equal lateraland medial collateral ligament tension. Alternatively, the soft tissuerelease can be performed to set different loadings in each compartmentrelative to one another. Equalizing the medial and lateral gap isdisclosed in FIG. 31 whereby the process of equalization reduces thetotal error of the femur and tibia in relation to the mechanical axis ofthe leg as discussed herein above for distractor 10.

In general, the prepared surface of the tibia is resected to align thetibia to the mechanical axis. Note that the distal end of the femur isforcibly aligned to have equal medial and lateral gaps at substantiallyequal loading in each compartment of the knee which is the process ofequalizing or equalization of the knee joint for receiving knee jointprosthetic components. In one embodiment, a guide hole jig can becoupled to distractor 1000 or to the distal end of the femur fordrilling guide holes for a bone cutting jig. The guide holes are drilledto align the cutting jig to cut one or more surfaces of the distal endof the femur to produce the equalized knee compartments. The guide holesare drilled at an angle that counters offset of the femur relative tothe mechanical axis whereby a prepared surface of the distal end of thefemur cut by the femoral cutting jig coupled to the guide holes producesan installed femoral prosthetic component that is aligned to themechanical axis.

Brake 610 can be released after drilling the guide holes for theequalization process using distractor 1000. Knob 616 can then be rotatedclockwise to bring the lateral plate 604 and medial plate 606 to aminimum height. The leg can then be placed in flexion. For example, theleg can be placed where the tibia is at a 90 degree angle relative tothe femur. A similar process to that disclosed herein above usingdistractor 1000 can be used to equalize the compartments in flexion. Inone embodiment, with the leg in flexion, knob 616 is rotated counterclockwise to raise lateral plate 604 and medial plate 606 into contactwith a posterior portion of the lateral condyle and a posterior portionof the medial condyle. Knob 616 is rotated counter clockwise until apredetermined load magnitude is measured. The load magnitude on themedial and lateral condyles can be viewed on the display coupled to thecomputer in real-time that receives load measurement data. Typically, asingle condyle will be at the predetermined load magnitude.

The brake is applied to the side that measures the predetermined loadmagnitude. For example, lateral plate 604 measures at the predeterminedload magnitude and brake 608 is applied. Medial plate 606 is free tomove by rotation of knob 616. Knob 616 is rotated counter clockwise toincrease the distraction distance between medial plate 606 and fixedposition plate 602 thereby increasing the load magnitude applied tomedial plate 606. The increase in load magnitude and the distractiondistance is displayed on the display coupled to the computer receivingload measurement data and distraction distance data. In one embodiment,the distraction distance between medial plate 606 and fixed positionplate 602 is increased until the predetermined load magnitude ismeasured. Thus, the load magnitude on medial plate 606 and lateral plate604 are equal to the predetermined load magnitude. The height of themedial compartment and the height of the lateral compartment can bedifferent at the predetermined load magnitude. For example the lateralcompartment height can be greater than the lateral compartment height.

Brake 608 is released with the load magnitude applied to the medialplate 606 equal to the load magnitude applied to the lateral plate 604.Brake 610 is enabled such that medial plate 606 cannot move. Knob 606 isrotated counter clockwise to increase the distraction distance betweenmedial plate 604 and fixed position plate 602. The distraction distanceis increased until the lateral compartment height is equal to the medialcompartment height. Increasing the distraction distance between lateralplate 604 and fixed position plate 602 will increase the tension on thelateral collateral ligament. After the medial compartment height and thelateral compartment height are equalized in flexion the tension on thelateral collateral ligament will be greater than the tension on themedial collateral ligament. In one embodiment, a drill guide can becoupled to distractor 1000 or the distal end of the femur 700. Drillguide holes are drilled into the distal end of the femur with the medialgap and the lateral gap equalized to support at least one bone cut forinstallation of a femoral prosthetic component. The load magnitudeapplied to the lateral plate 604 and the medial plate 606 can also beequalized. For example, soft tissue release can be used to reduce thetension of the lateral collateral ligament until the measured loadmagnitude on the lateral plate 604 equals the load magnitude on themedial plate 606. Thus, the installation of the femoral prostheticcomponent on the distal end of femur 700 results in the medialcompartment of the knee joint spaced equal to the lateral compartment(or a spacing chosen by the surgeon), equal load magnitudes applied ineach compartment (or a load distribution chosen by the surgeon), withthe leg in alignment to the mechanical axis. Note also that theequalization is performed in the leg in extension and flexion therebymaintaining the alignment and balance throughout the range of motion. Ingeneral, the measurement data generated during the use of distractor1000 should correspond to measurement data generated after installationof the final prosthetic components of the knee joint.

FIG. 51 depicts an exemplary diagrammatic representation of a machine inthe form of a system 4100 within which a set of instructions, whenexecuted, may cause the machine to perform any one or more of themethodologies discussed above. In some embodiments, the machine operatesas a standalone device. In some embodiments, the machine may beconnected (e.g., using a network) to other machines. In a networkeddeployment, the machine may operate in the capacity of a server or aclient user machine in server-client user network environment, or as apeer machine in a peer-to-peer (or distributed) network environment.

The machine may comprise a server computer, a client user computer, apersonal computer (PC), a tablet PC, a laptop computer, a desktopcomputer, a control system, logic circuitry, a sensor system, an ASIC,an integrated circuit, a network router, switch or bridge, or anymachine capable of executing a set of instructions (sequential orotherwise) that specify actions to be taken by that machine. It will beunderstood that a device of the present disclosure includes broadly anyelectronic device that provides voice, video or data communication.Further, while a single machine is illustrated, the term “machine” shallalso be taken to include any collection of machines that individually orjointly execute a set (or multiple sets) of instructions to perform anyone or more of the methodologies discussed herein.

System 4100 may include a processor 4102 (e.g., a central processingunit (CPU), a graphics processing unit (GPU, or both), a main memory4104 and a static memory 4106, which communicate with each other via abus 4108. System 4100 may further include a video display unit 4110(e.g., a liquid crystal display (LCD), a flat panel, a solid statedisplay, or a cathode ray tube (CRT)). System 4100 may include an inputdevice 4112 (e.g., a keyboard), a cursor control device 4114 (e.g., amouse), a disk drive unit 4116, a signal generation device 4118 (e.g., aspeaker or remote control) and a network interface device 4120.

The disk drive unit 4116 can be other types of memory such as flashmemory and may include a machine-readable medium 4122 on which is storedone or more sets of instructions (e.g., software 4124) embodying any oneor more of the methodologies or functions described herein, includingthose methods illustrated above. Instructions 4124 may also reside,completely or at least partially, within the main memory 4104, thestatic memory 4106, and/or within the processor 4102 during executionthereof by the system 4100. Main memory 4104 and the processor 4102 alsomay constitute machine-readable media.

Dedicated hardware implementations including, but not limited to,application specific integrated circuits, programmable logic arrays andother hardware devices can likewise be constructed to implement themethods described herein. Applications that may include the apparatusand systems of various embodiments broadly include a variety ofelectronic and computer systems. Some embodiments implement functions intwo or more specific interconnected hardware modules or devices withrelated control and data signals communicated between and through themodules, or as portions of an application-specific integrated circuit.Thus, the example system is applicable to software, firmware, andhardware implementations.

In accordance with various embodiments of the present disclosure, themethods described herein are intended for operation as software programsrunning on a computer processor. Furthermore, software implementationscan include, but not limited to, distributed processing orcomponent/object distributed processing, parallel processing, or virtualmachine processing can also be constructed to implement the methodsdescribed herein.

The present disclosure contemplates a machine readable medium containinginstructions 4124, or that which receives and executes instructions 4124from a propagated signal so that a device connected to a networkenvironment 4126 can send or receive voice, video or data, and tocommunicate over the network 4126 using the instructions 4124. Theinstructions 4124 may further be transmitted or received over a network4126 via the network interface device 4120.

While the machine-readable medium 4122 is shown in an example embodimentto be a single medium, the term “machine-readable medium” should betaken to include a single medium or multiple media (e.g., a centralizedor distributed database, and/or associated caches and servers) thatstore the one or more sets of instructions. The term “machine-readablemedium” shall also be taken to include any medium that is capable ofstoring, encoding or carrying a set of instructions for execution by themachine and that cause the machine to perform any one or more of themethodologies of the present disclosure.

The term “machine-readable medium” shall accordingly be taken toinclude, but not be limited to: solid-state memories such as a memorycard or other package that houses one or more read-only (non-volatile)memories, random access memories, or other re-writable (volatile)memories; magneto-optical or optical medium such as a disk or tape; andcarrier wave signals such as a signal embodying computer instructions ina transmission medium; and/or a digital file attachment to e-mail orother self-contained information archive or set of archives isconsidered a distribution medium equivalent to a tangible storagemedium. Accordingly, the disclosure is considered to include any one ormore of a machine-readable medium or a distribution medium, as listedherein and including art-recognized equivalents and successor media, inwhich the software implementations herein are stored.

Although the present specification describes components and functionsimplemented in the embodiments with reference to particular standardsand protocols, the disclosure is not limited to such standards andprotocols. Each of the standards for Internet and other packet switchednetwork transmission (e.g., TCP/IP, UDP/IP, HTML, HTTP) representexamples of the state of the art. Such standards are periodicallysuperseded by faster or more efficient equivalents having essentiallythe same functions. Accordingly, replacement standards and protocolshaving the same functions are considered equivalents.

FIG. 52 is an illustration of a communication network 4200 formeasurement and reporting in accordance with an exemplary embodiment.Briefly, the communication network 4200 expands broad data connectivityto other devices or services. As illustrated, the measurement andreporting system 4255 can be communicatively coupled to thecommunications network 4200 and any associated systems or services.

As one example, measurement system 4255 can share its parameters ofinterest (e.g., angles, load, balance, distance, alignment,displacement, movement, rotation, and acceleration) with remote servicesor providers, for instance, to analyze or report on surgical status oroutcome. This data can be shared for example with a service provider tomonitor progress or with plan administrators for surgical monitoringpurposes or efficacy studies. The communication network 4200 can furtherbe tied to an Electronic Medical Records (EMR) system to implementhealth information technology practices. In other embodiments, thecommunication network 4200 can be communicatively coupled to HISHospital Information System, HIT Hospital Information Technology and HIMHospital Information Management, EHR Electronic Health Record, CPOEComputerized Physician Order Entry, and CDSS Computerized DecisionSupport Systems. This provides the ability of different informationtechnology systems and software applications to communicate, to exchangedata accurately, effectively, and consistently, and to use the exchangeddata.

The communications network 4200 can provide wired or wirelessconnectivity over a Local Area Network (LAN) 4201, a Wireless Local AreaNetwork (WLAN) 4205, a Cellular Network 4214, and/or other radiofrequency (RF) system (see FIG. 4). The LAN 4201 and WLAN 4205 can becommunicatively coupled to the Internet 4220, for example, through acentral office. The central office can house common network switchingequipment for distributing telecommunication services. Telecommunicationservices can include traditional POTS (Plain Old Telephone Service) andbroadband services such as cable, HDTV, DSL, VoIP (Voice over InternetProtocol), IPTV (Internet Protocol Television), Internet services, andso on.

The communication network 4200 can utilize common computing andcommunications technologies to support circuit-switched and/orpacket-switched communications. Each of the standards for Internet 4220and other packet switched network transmission (e.g., TCP/IP, UDP/IP,HTML, HTTP, RTP, MMS, SMS) represent examples of the state of the art.Such standards are periodically superseded by faster or more efficientequivalents having essentially the same functions. Accordingly,replacement standards and protocols having the same functions areconsidered equivalent.

The cellular network 4214 can support voice and data services over anumber of access technologies such as GSM-GPRS, EDGE, CDMA, UMTS, WiMAX,2G, 3G, WAP, software defined radio (SDR), and other known technologies.The cellular network 4214 can be coupled to base receiver 4210 under afrequency-reuse plan for communicating with mobile devices 4202.

The base receiver 4210, in turn, can connect the mobile device 4202 tothe Internet 4220 over a packet switched link. The internet 4220 cansupport application services and service layers for distributing datafrom the measurement system 4255 to the mobile device 4202. Mobiledevice 4202 can also connect to other communication devices through theInternet 4220 using a wireless communication channel.

The mobile device 4202 can also connect to the Internet 4220 over theWLAN 4205. Wireless Local Access Networks (WLANs) provide wirelessaccess within a local geographical area. WLANs are typically composed ofa cluster of Access Points (APs) 4204 also known as base stations. Themeasurement system 4255 can communicate with other WLAN stations such aslaptop 4203 within the base station area. In typical WLANimplementations, the physical layer uses a variety of technologies suchas 802.11b or 802.11g WLAN technologies. The physical layer may useinfrared, frequency hopping spread spectrum in the 2.4 GHz Band, directsequence spread spectrum in the 2.4 GHz Band, or other accesstechnologies, for example, in the 5.8 GHz ISM band or higher ISM bands(e.g., 24 GHz, etcetera).

By way of the communication network 4200, the measurement system 4255can establish connections with a remote server 4230 on the network andwith other mobile devices for exchanging data. The remote server 4230can have access to a database 4240 that is stored locally or remotelyand which can contain application specific data. The remote server 4230can also host application services 4250 directly, or over the internet4220.

In general, a robot can support or assist the distraction of a kneejoint in under control of a surgeon. The distractor 10 or distractor1000 disclosed herein above can be coupled to the robot. One example ofthe robot is the Robodoc surgical robot with a robotic assisted TKAapplication. A robot can also include surgical CNC robots, surgicalhaptic robots, surgical teleoperative robots, surgical hand-held robots,or any other surgical robot. Distractor 10 can be automated to couple toand work with the robot thereby replacing direct hand control by thesurgeon. The actions taken by the robot in control of distractor 10 canbe smoother and more accurate by having the robot use the measurementdata in real-time and providing feedback to distractor 10 for subsequentsteps. An added benefit can be shortening the time of surgery thatreduces the time a patient is under anesthesia.

The robot can be configured to perform computer-assisted surgery andmore specifically knee surgery with distractor 10. Typically, the robotand distractor 10 is used for computer-assisted surgery to improveperformance, reduce time, and minimize variation in the distraction,alignment, bone cuts, and installation of one or more prostheticcomponents for a prosthetic knee joint. The robot can controldistraction, medial-lateral tilt, loading, tissue release, braking, anddrilling guide holes using the real-time measurement data sent fromdistractor 10.

In general, measurement data from distractor 10 can be wirelesslytransmitted to a computer of the robot. Alternatively, the measurementdata can be hard wired to the robot. Examples of measurement data fromdistractor 10 can be position data, distraction distance, load,medial-lateral tilt, or other data relevant to a prosthetic kneeinstallation. The measurement data received by the robot can be furtherprocessed to calculate and display measurement data needed by thesurgeon for the distraction and preparation of the bone surfaces of theknee joint. The prepared bone surfaces will receive a prostheticcomponent that supports alignment to the mechanical axis of the leg. Inone embodiment, the computer includes one or more algorithms that areused at various stages of the surgery. The measurement data is input tothe algorithms of the robot and the algorithms can convert the data intoinformation displayed on the display for robotic actions that are usedto make bone cuts, pin placements, prosthetic component sizing, etc. . .. or provide feedback on actions that the surgeon may take. The feedbackmay take the form of audible, visual, or haptic feedback that guides thesurgeon on the distraction or subsequent steps taken by the robot tosupport or resist an action based on the measurement data. The feedbackcan also smooth or prevent motions by a user that could be detrimentalto the surgery. Furthermore, the status of the measurement data can beused to generate a workflow that is subsequently implemented by asurgeon or automatically by the robot to enhance performance andreliability of the knee joint installation.

Referring to FIGS. 1-3, a surgical apparatus 10 is disclosed comprisinga fixed support structure 28, a moving support structure 30, and adistraction mechanism 24. Distraction mechanism 24 moves moving supportstructure 30 relative to fixed support structure 28. Fixed supportstructure 28 couples to housing 20 of surgical support apparatus 10.Fixed support structure 28 includes a frame 36 having an opening. In oneembodiment, a portion of distraction mechanism 24 is housed in housing20. Moving support structure 30 couples to a distal end of femur 16.Frame 36 of fixed support structure 36 couples to a proximal end oftibia 18. In one embodiment, the proximal end of tibia 18 has a preparedbone surface. The prepared bone surface is cut referenced to theanatomical or mechanical axis of the leg. The prepared bone surface canhave a predetermine anterior-posterior (A-P) slope. In one embodiment,bottom surface 34 couples to the prepared bone surface around aperiphery. In one embodiment, the leg is placed in extension whensurgical apparatus 10 is inserted. Typically, surgical apparatus 10 isinserted with the moving support structure 30 and the fixed supportstructure 28 in a minimum height position. In one embodiment, movingsupport structure 30 fits within frame 36. In one embodiment, theminimum height position corresponds to a bottom surface 34 of frame 36and a bottom surface of moving support structure 30 coupling to theprepared bone surface of tibia 18. In one embodiment, the bottom surface34 of frame 36 is co-planar to bottom surface 42 of moving supportstructure 30 when in the minimum height position.

In one embodiment, a module 32 having a cover 38 is aligned and retainedto moving support structure 30. Module 32 includes electronic circuitryand one or more sensors to measure one or more parameters. Module 32 isconfigured to control a measurement process and to transmit modulemeasurement data. In one embodiment, module 32 can measure leg position,load magnitude applied to the medial or lateral sides of module 32,position of load on the medial or lateral side of module 32, alignment,and other parameters. The module measurement data is transmitted to acomputer 12 having a display 14. The module measurement data can beprocessed and displayed in different formats on display 14 to provideinformation at a glance.

Similarly, surgical apparatus 10 can have electronic circuitry and oneor more sensors. The electronic circuitry can control a measurementprocess and transmit apparatus measurement data. In one embodiment,surgical apparatus 10 can measure a M-L tilt angle, a first compartmentheight, a second compartment height, or an average of the first andsecond compartment heights and display the apparatus measurement data ondisplay 14 of computer 12. The apparatus measurement data can betransmitted to computer 12 for further processing and displayed ondisplay 14. In one embodiment, the M-L tilt angle can be measured by aHall Effect Sensor coupled to moving support structure 30. The height ofthe first compartment or the height of the second compartment can bemeasured by a Linear Hall Sensor coupled to moving support structure 30.Alternatively, one or more gauges can be placed on surgical apparatus 10for viewing by the user. The one or more gauges can be mechanical orelectrical gauges.

A distraction mechanism 24 of surgical apparatus 10 is configured toraise and lower the moving support structure 30 relative to fixedsupport structure 28. In one embodiment, distraction mechanism includesat least one gear such as gear 122 of FIG. 14. In general, distractionmechanism 24 is adjusted in height until a first compartment of the kneejoint is at a first predetermined load value. Typically the firstpredetermined load value is in a range of 20-40 lbs of loading. In oneembodiment, moving support structure 30 can pivot medially or laterallyas the height is adjusted to the first predetermined load value. Movingsupport structure 30 can freely pivot when M-L tilt mechanism 22 isdisengaged. In one embodiment, M-L tilt mechanism 22 is between movingsupport structure 30 and distraction mechanism 24. M-L tilt mechanism 22includes a pivot or pivot point on which moving support structure 30pivots. The second compartment will measure a loading less than thefirst predetermined load value. In one embodiment, the height of thesecond compartment will also be less than the height of the firstcompartment. The use of the term first compartment is arbitrary as itcan be either the medial compartment or the lateral compartment of theknee joint being set to the first predetermined load value initially.For example, if the first compartment at the first predetermined loadvalue is the medial compartment then a second compartment is the lateralcompartment. Conversely, if the first compartment at the firstpredetermined load value is the lateral compartment then the secondcompartment is the medial compartment.

The first and second compartments typically are at different heightswhen the first compartment is at the first predetermined load value. Asmentioned previously, moving support structure 30 is allowed to swingmedial or laterally as the loading is increased by increasing the heightof the first compartment. After setting the first compartment to thefirst predetermined load value a distraction lock mechanism 124 of FIG.14 is engaged. In one embodiment, distraction lock mechanism 124 iscouples to gear 128 thereby preventing knob 26 from rotating.Distraction lock mechanism 124 prevents a height of moving supportstructure from changing. M-L (medial-lateral) tilt mechanism 22 is thenengaged to equalize the first and second compartments. Moving supportstructure 30 will no longer freely pivot medially or laterally when M-Ltilt mechanism 22 is engaged. In one embodiment, a process ofequalization requires the second compartment to be forcibly raised untilit is at the first predetermined height of the first compartment. TheM-L tilt angle will be at zero when the first and second compartmentsare equalized. The M-L tilt angle is measured by the Hall Effect Sensoror a gauge on the surgical apparatus. The medial and lateral compartmentheight or the average compartment height is measured by the Linear HallSensor or a gauge. The first M-L tilt angle corresponds to an alignmenterror that is reduced by equalization and introduced into a bone cut. Inone embodiment, loading on the first or second compartments can beadjusted or fine-tuned after equalization. For example, soft tissuetensioning can be performed to change loading with the load measurementsbeing monitored on display 14 in real-time.

In general, at least one bone cut is made to femur 16 in extension tosupport installation of a femoral prosthetic component with the M-L tiltangle or equalization incorporated in the bone cut to reduce alignmenterror. The at least one bone cut relates to the first and secondcompartments equalized and the M-L tilt angle. The equalized first andsecond compartment reduces the alignment error of the femur as shown inFIG. 32 thereby rendering a knee joint installation having a femur 400and tibia 402 in improved alignment with a mechanical axis of the leg.The bone cut also supports installation of the femoral prostheticcomponent incorporating the reduced alignment error. Referring to FIG.34, a drill guide 402 is configured to couple to surgical apparatus 10.In one embodiment, surgical apparatus 10 includes a drill guideretaining device to retain and align drill guide 402 for drilling two ormore holes for mounting a bone cutting jig. In one embodiment drillguide 402 is aligned to femur 400 and at least two holes are drilled.The at least two holes drilled correspond to or are related to the M-Ltilt measured when the first compartment and the second compartment areequalized. A bone cutting jig can be mounted to the at least two holesand a bone cut is made to femur 400 to support installation of a femoralprosthetic component. In general, installation of the femoral prostheticcomponent will have load measurements in the medial compartment and thelateral compartment similar to the first predetermined load value inextension and improved alignment to the mechanical axis of the leg inextension.

Referring to FIGS. 36-43, surgical apparatus 10 is placed at the minimumheight with the leg is moved into flexion. In one embodiment, the leg isplaced at a 90 degree angle. In general, the process listed below isdone at least once in flexion but can be done more than one time atdifferent flexion angles to optimize performance of the knee joint overthe range of motion. In general, with the leg in flexion distractionmechanism 24 is adjusted in height until one of the first compartment orthe second compartment of the knee joint is at a second predeterminedload value. The second predetermined load value can be the same as thefirst predetermined load value or it can be different. Moving supportstructure 30 is allowed to pivot medially or laterally as the height isadjusted to the second predetermined load value in flexion. Similar tothe leg in extension, the height of the first compartment in flexion,the height of the second compartment in flexion, leg position, therotation balance angle in flexion, loading on the first compartment inflexion, loading on the second compartment, in flexion, contact point onthe first compartment, and contact point on the second compartment areall monitored and captured in real-time.

Equalization is performed using surgical apparatus 10 in which movingsupport structure 30 is no longer allowed to swing freely. Distractionlock mechanism 124 is engaged to prevent distraction mechanism 24 fromraising or lowering moving support structure 30. M-L tilt mechanism 22is engaged to forcibly change the M-L tilt angle under user control suchthat the first and second compartments in flexion have equal compartmentheights. Engaging M-L tilt mechanism 22 prevents moving supportstructure 30 from freely pivoting medially or laterally. In oneembodiment, the compartment (medial or lateral) not at the secondpredetermined load value is forcibly changed to have an equal height asthe compartment at the second predetermined load value. In oneembodiment, the compartment not at the second predetermined load valuewill have a height less than the compartment at the second predeterminedload value. The rotation balance angle corresponds to the M-L tilt angleof moving support structure 30 with the leg in flexion at the secondpredetermined value. After equalization the M-L tilt angle will be zero.In one embodiment, the loading applied to the first compartment and thesecond apartment can be adjusted. For example, soft tissue tensioningcan be performed. The measurement data is transmitted, processed bycomputer 12, and displayed by display 14.

Referring to FIGS. 39-43, sizers 510, 540, 542, 544, and 546 are used todetermine implant size of the femoral prosthetic component. In theexample, sizer 510 is configured to be coupled to surgical apparatus 10.Different sizers can be installed and coupled to the femur to support afemoral prosthetic component choice. The surgical apparatus 10 isconfigured to support drilling two or more holes in the femur in flexionin support of one of sizers 510, 540, 542, 544, and 546. The two or moreholes drilled into the femur in flexion correspond to the balancedrotation angle. A cutting jig can be coupled to the two or more holes tomake one or more bone cuts to support installation of the femoralprosthetic component with the first and second compartments equalized inflexion.

A method of decreasing musculoskeletal alignment error is disclosedusing surgical apparatus 10. The method can be practiced with more orless than the steps shown, and is not limited to the order of stepsshown. The method is not limited to the knee joint example but can beused for hip, shoulder, ankle, elbow, spine, hand, foot, bone, and otherareas musculoskeletal system. The method can be referred to in FIGS. 1-3and FIGS. 26-50. In a first step, a surgical apparatus 10 is insertedinto a knee joint with a leg in extension. A frame 36 of a fixed supportstructure 28 couples to a prepared surface of a tibia. A bottom surface42 of a moving support structure contacts the prepared surface of thetibia. The first compartment of the knee joint is distracted to a firstpredetermined load value. Surgical apparatus 10 includes a distractionmechanism 24 configured to distraction a first compartment, a secondcompartment, or both compartments. Typically, the load value is selectedwithin a range of 20-40 lbs of loading. Alternatively, the load valuecan be selected from a range of 20-60 lbs of loading. Moving supportstructure 30 is configured to pivot freely medially or laterally.

Frame 36 of fixed support structure 28 has an opening. In oneembodiment, the opening is larger than moving support structure 30.Moving support structure 30 is configured to fit with the opening offrame 36. In one embodiment, moving support structure 30 can be loweredby distraction mechanism 24 within frame 36 such that bottom surface 42of moving support structure 30 contacts the prepared surface of thetibia during insertion. In one embodiment, moving support structure 30contacting the prepared surface of the tibia is a minimum height thatsurgical apparatus 10 can achieve. In one embodiment, frame 36 surroundsat least a portion of moving support structure 30. Frame 36 is rigid anddoes not flex during distraction. In one embodiment, moving supportstructure 30 can be lowered within frame 36 whereby bottom surface 34 offrame 36 and support structure 28 is co-planar to bottom surface 42 ofmoving support structure 30.

In a second step, a module 32 is placed on moving support structure 30prior to insertion. A cover 38 can also be placed on moving supportstructure 30. Module 32 can include electronic circuitry 150, a powersource 60, and one or more sensors. Electronic circuitry 150 isconfigured to control a measurement process and transmit measurementdata to a computer 12. Computer 12 can receive, process, and display themeasurement data on a display 14. In one embodiment, module 32 canmeasure position, leg position, alignment, loading on a medialcompartment and a lateral compartment, position of load on the medialand lateral compartments, rotation, and other parameters in real-time.

In a third step, the medial-lateral (M-L) tilt angle of moving supportstructure 30 is measured and displayed on display 14 of computer 12. Inone embodiment, the M-L tilt angle is measured by a Hall Effect sensorin surgical apparatus 10. The distraction height of the medial compart,the lateral compartment, or average height is measured and displayed ondisplay 14 of computer 12. In one embodiment, the distraction height ismeasured by a Linear Hall sensor. In one embodiment, electroniccircuitry 150 is coupled to the Hall Effect Sensor and the Linear Hallsensor in surgical apparatus 10. Electronic circuitry 150 is configuredto control the measurement of the M-L tilt angle and distraction heightand transmit the measurement data.

In a fourth step, distraction mechanism 24 is locked. A distraction lockmechanism is engaged to prevent movement of distraction mechanism 24. Inone embodiment, distraction mechanism 24 comprises one or more gears. Inone embodiment, distraction lock mechanism 124 couples to one or moreteeth of the one or more gears such that the one or more gears cannotmove thereby locking the distraction mechanism 24 at a heightcorresponding to the predetermined load value.

In a fifth step, the first and second compartments are equalized.Equalization is a process of raising a height of the second compartmentto equal the first compartment height at the predetermined load value.Equalizing the first and second compartments reduces alignment error ofthe leg. In one embodiment, at least one bone cut is made to a femur forreceiving a femoral prosthetic component that reduces alignment error ofthe leg. The at least one bone cut takes into account the equalizationor M-L tilt angle to reduce the alignment error when the femoralprosthetic component is installed on the femur. In one embodiment, theloading of the first or second compartment can be adjusted.

In a sixth step, the process of equalization engages the M-L tiltmechanism 22 of surgical apparatus 10. In one embodiment, M-L tiltmechanism 22 comprises at least one worm gear. M-L tilt mechanism 22when disengaged allows moving support structure 30 to freely swingmedially and laterally. M-L tilt mechanism 22 has a pivot or a pivotpoint that supports medial or lateral movement. M-L tilt mechanism 22when engaged prevents moving support structure 30 from freely movingmedially or laterally. In one embodiment, M-L tilt mechanism 22 isengaged to forcibly change the M-L tilt angle to zero under usercontrol. Changing the M-L tilt angle to zero equalizes the secondcompartment height equal to the first compartment height that is at thepredetermined load value. In one embodiment, M-L tilt mechanism 22 iscoupled between distraction mechanism 24 and moving support structure30. In one embodiment, M-L tilt mechanism 22 is self-locking.

In a seventh step, a drill guide 492 is coupled to surgical apparatus10. At least two holes 496 are drilled into the femur. The orientationof the at least two holes 496 relate to the equalization or the M-L tiltangle. A bone cutting jig is coupled to a distal end of a femur throughthe at least two holes 496. The bone cutting jig is aligned to cut thefemur oriented to the at least two holes 496 and at least one bone cutis made. A femoral prosthetic component is coupled to and aligned to theat least one bone cut. The femoral prosthetic component is oriented onthe femur to reduce alignment error of the leg where the orientationrelates to the equalization or the M-L tilt angle.

It should be noted that very little data exists on implanted orthopedicdevices. Most of the data is empirically obtained by analyzingorthopedic devices that have been used in a human subject or simulateduse. Wear patterns, material issues, and failure mechanisms are studied.Although, information can be garnered through this type of study it doesyield substantive data about the initial installation, post-operativeuse, and long term use from a measurement perspective. Just as eachperson is different, each device installation is different havingvariations in initial loading, balance, and alignment. Having measureddata and using the data to install an orthopedic device will greatlyincrease the consistency of the implant procedure thereby reducingrework and maximizing the life of the device. In at least one exemplaryembodiment, the measured data can be collected to a database where itcan be stored and analyzed. For example, once a relevant sample of themeasured data is collected, it can be used to define optimal initialmeasured settings, geometries, and alignments for maximizing the lifeand usability of an implanted orthopedic device.

The present invention is applicable to a wide range of medical andnonmedical applications including, but not limited to, frequencycompensation; control of, or alarms for, physical systems; or monitoringor measuring physical parameters of interest. The level of accuracy andrepeatability attainable in a highly compact sensing module or surgicalapparatus may be applicable to many medical applications monitoring ormeasuring physiological parameters throughout the human body including,not limited to, bone density, movement, viscosity, and pressure ofvarious fluids, localized temperature, etc. with applications in thevascular, lymph, respiratory, digestive system, muscles, bones, andjoints, other soft tissue areas, and interstitial fluids.

While the present invention has been described with reference toparticular embodiments, those skilled in the art will recognize thatmany changes may be made thereto without departing from the spirit andscope of the present invention. Each of these embodiments and obviousvariations thereof is contemplated as falling within the spirit andscope of the invention.

What is claimed is:
 1. A surgical apparatus comprising: a housing; adistraction mechanism wherein at least a portion of the distractionmechanism is in the housing; a fixed support structure coupled to thehousing wherein the support structure includes a frame and wherein theframe is configured to couple to a prepared surface of a tibia; and amoving support structure coupled to the distraction mechanism whereinthe moving support structure is configured to pivot medially orlaterally, wherein the distraction mechanism is configured to raise orlower the moving support structure relative to the fixed supportstructure, wherein the surgical apparatus is configured to distract aknee joint with a leg in extension, wherein the distraction mechanismcomprises at least one gear to support moving the moving supportstructure, wherein a M-L tilt mechanism is coupled between the movingsupport structure and the distraction mechanism, wherein the movingsupport structure is configured to be raised until a first compartmentof the knee joint is at a predetermined load value, and wherein themoving support structure is locked to prevent movement.
 2. The surgicalapparatus of claim 1 wherein the distraction mechanism can move themoving support structure such that a bottom surface of the movingsupport structure is co-planar to a bottom surface of the fixed supportstructure.
 3. The surgical apparatus of claim 1 wherein the surgicalapparatus includes a magnetic distance sensor configured to measure aheight of the first compartment.
 4. The surgical apparatus of claim 1wherein the moving support structure is configured to fit within anopening of the frame.
 5. The surgical apparatus of claim 1 wherein a M-Ltilt angle of the moving support structure is measured, wherein the M-Ltilt mechanism is engaged to forcibly equalize a height of a secondcompartment of the knee joint to the height of the first compartment,and wherein the equalization or M-L tilt angle is reflected in at leastone bone cut for installation of a femoral prosthetic component toreduce alignment error of the leg or bring the knee joint in balance. 6.A surgical apparatus comprising: a housing; a distraction mechanismwherein at least a portion of the distraction mechanism is in thehousing; a fixed support structure coupled to the housing wherein thesupport structure includes a frame and wherein the frame is configuredto couple to a prepared surface of a tibia; and a moving supportstructure coupled to the distraction mechanism wherein the movingsupport structure is configured to pivot medially or laterally, whereinthe distraction mechanism is configured to raise or lower the movingsupport structure relative to the fixed support structure, wherein thesurgical apparatus is configured to distract a knee joint with a leg inextension, wherein the moving support structure is raised until a firstcompartment of the knee joint is at a predetermined load value, whereina M-L tilt mechanism of the surgical apparatus is configured to forciblyequalize a height of a second compartment of the knee joint to theheight of the first compartment, and wherein the equalization of thefirst and second compartments or an M-L tilt angle is reflected in atleast one bone cut for installation of a femoral prosthetic component toreduce alignment error of the leg or bring the knee joint in balance. 7.The surgical apparatus of claim 6 wherein the M-L tilt mechanism iscoupled between the moving support structure and the distractionmechanism and wherein the moving support structures is configured to fitwithin an opening of the frame.
 8. The surgical apparatus of claim 6wherein the moving support structure is configured to fit within anopening of the frame.
 9. The surgical apparatus of claim 8 wherein thedistraction mechanism can move the moving support structure such that abottom surface of the moving support structure is co-planar to a bottomsurface of the fixed support structure.
 10. The surgical apparatus ofclaim 6 wherein distraction mechanism comprises at least one gear tosupport moving the moving support structure.
 11. The surgical apparatusof claim 6 wherein the M-L tilt angle is measured by a Hall Effectsensor on the surgical apparatus.
 12. The surgical apparatus of claim 6wherein the first compartment height of the knee joint is measured by asensor on the surgical apparatus.